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Inexpensive Software Defined Radio Spectrum Analyzer < $10.00

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Old 03-12-2014, 04:00 PM   #1  
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Default Inexpensive Software Defined Radio Spectrum Analyzer < $10.00

Last December “majortom” a frequent contributor to the Canadian TV Digital Home forum posted VHF & UHF TV spectrum analyzer screen captures that looked very informative. What intrigued me was the graphics were captured using a < $10.00 RTL2832U + R820T DVB-T USB tuner card Software Defined Radio (SDR) and free open source Spectrum Analyzer software.

Here is a partial scan of my UHF environment:

The scan was conducted using my new SDR fed by a 2-Way splitter that also fed my Hauppauge tuner so both devices should essentially see the same signal strength & quality. The TV Fool & SNR information was added using Windows Paint.

SDR’s are produced with a minimum of hardware (read cheaply) and implement in software all or most of the costly components that have historically been implemented in hardware (i.e., amplifiers, mixers, filters, detectors, etc.). These amazing little devices are capable of tuning over a range of 24 MHz to 1.7+ GHz with good sensitivity.

I ordered one through eBay, from China, that cost $8.72 w/free shipping (prices will vary slightly depending on Exchange rate). My first one took 17 days to arrive by ePacket. I was so impressed with its performance that after a couple of weeks I ordered two more and they arrived in 13 days. I was charged $8.66½ ea. for these two.
Here is the link to where I ordered my tuners:

The supplied antenna connects to the side of the USB tuner card with an MCX male plug. To easily interface with RG-6/’F’ connectors I also ordered an ‘F’ jack (female) to MCX plug pigtail. (Note; other RTL2832U DVB-T USB tuners are available that use a different style connector mounted in the end of the dongle so verify which style cable you need before you order.) These cost $5.80 and the Chinese vendor charges $1.00 for ePacket delivery from China. My first cable arrived a couple of days before my first tuner. I ordered two more cables when I ordered the two tuners mentioned above. The tuners came yesterday but I’m still waiting on the remaining cables.
Here is the link to where I ordered my cables:

Installing the SDR on a computer

Don't install the software on the CD that comes with the dongle. It is for use in Europe and won’t work with US ATSC TV anyway.

As with most USB devices when you plug your dongle in for the first time Windows will offer to install a driver. Again, exit out of the Windows offer.

Install USB driver for SDR dongle
What you need to use is an open source driver named Zadig. Zadig is used to replace the Windows driver so the RLTSDR driver can access the dongle. Note that different versions of Zadig are required for different Windows versions (XP = zadig_xp_2.1.0, Vista & later = zadig_2.1.0, etc) and you will need to run Zadig for the specific USB port you use your dongle in as windows only applies this driver to the selected devices port. Make sure to select “Bulk-In, Interface (Interface 0)” from the dropdown window. Also, make sure you don’t accidently configure it on a port your keyboard and/or mouse is on because it could stop them from working. Here is a link to download Zadig with instructions on how to configure it:

Install Application(s)

There are two applications that I’ve been using.

The first is RTLSDR Scanner. This application provides the wideband spectrum display shown above. A Windows installer can be downloaded from SourceForge that installs the application and all of its dependencies. I have used this installer to install RTLSDR Scanner to both XP (SP-3) and Windows 7.

Here is a link to the authors Home Page:

Here is a link to download the install script from SourceForge:

I recommend making an XP directory under “C:\Program Files” or for Windows 7 “C:\Program Files (x86)” to download and install from.

The following dependencies get installed:
Python 2.6 or greater
So be prepared for the process to take a few minutes. Once all the dependencies are installed go to the RTLSDR Scanner program group and launch “Setup” to download and install the latest version of the RTLSDR Scanner program. “Setup” can also be run in the future to install new versions of RTLSDR Scanner as they are released.

The second is SDR# (read SDR Sharp). This application also offers a Spectrum Analyzer display but additionally, can produce a Waterfall display or can simultaneously display both. When you see a signal on the FFT you can click on it, automatically tuning to it and opening the audio channel. It also lets you store frequencies (in groups) for later recall. I’ve already created groups for FM Broadcast, Weather Radio, VHF & UHF Air bands (I live 4 miles from March ARB), 10 Meter Ham band and 6 Meter, 2 Meter and 220 MHz Amateur repeaters. This amazing program also demodulates CW, AM (including DSB, LSB & USB) and both Wide (FM broadcast) and Narrow band FM (police, fire & Amateur radio).

Here is a link to the SDR# Home Page:

There is a downloads tab on the home page where you can download the SDR# stable release or further down the page a link to a quick installation script to get the latest development version.

Most mass produced dongles, while more than accurate enough for their intended purpose, will exhibit a small frequency error. This is due to the crystal reference oscillator that runs at ~28.8 MHz being slightly off frequency. Hopefully, in the next few days I can find time to write-up simple frequency calibration procedure to remove this offset error.

Last edited by Pete Higgins; 03-16-2014 at 08:03 PM.. Reason: Add "Setup" information
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Old 03-12-2014, 07:15 PM   #2  
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Very interesting Pete, I've been watching your interest over there as well. I'll have to now take the time and decide if I want to wander down this path. Must say one should learn a lot about their signals this way.

I'll also need more time to absorb your typical well written/researched post. Thanks for all the links, this will make it easy for folks.
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Old 03-15-2014, 09:26 PM   #3  
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Assuming I had a cheap notebook computer could this work to point antennas or should I get the Digiair Pro 2? I used a cheap $150 notebook computer to point wireless internet antennas before.
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Old 03-15-2014, 10:29 PM   #4  
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In my opinion, the RTLSDR Scanner application would be too slow responding to be very useful for any more than crude antenna pointing. SDR# which views a single channel’s spectrum and seems to respond faster might work better but I think you would still find it awkward to interpret small dB changes. Besides, what I’m finding with ATSC digital signals is that Signal-to-Noise Ratio (SNR) has much more influence on good reception than raw signal strength. I have Hauppauge HVR-1800 tuner cards and use the signal meter that comes with their V7.0 software when pointing my antennas. It responds rapidly and shows SNR, correctable errors and uncorrectable errors. Both of my Samsung TV’s have signal strength meters that when peaked sometimes yield picture breakup but aligning my antenna arrays off peak for best SNR yields a stable picture. To be fair, I live in a very challenging signal environment (1 local TV & FM station 3.5 miles away in line with the 1 & 2-Edge stations I want 52 miles away). All of my antennas have rotors and I have to “peak” their positioning for reliable reception –hence the need for rapid feedback.

I think the Digiair Pro 2 might be discontinued and from what I’ve read it might not have enough sensitivity for weak signal environments where antenna pointing becomes much more critical. I would definitely research it before laying out almost $200.00.

Good luck, and if you find a good solution please share it with the community.
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Old 03-15-2014, 11:18 PM   #5  
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I think you are talking about the old digiair. This is the newer one and it runs about $325-$400. http://www.solidsignal.com/pview.asp...-ATSC&ss=62078
I haven't done many installs latley but for some reason my name has been coming up when people search for antenna installers in my area so I need to get ready. I live within 40 miles of the Salt Lake City area so I it is a very easy area for finding reception. The main channels that I will really need to worry about 90% of the time are on fairly powerful antennas 4000ft above the valley floor within a few miles of each other.
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Old 03-15-2014, 11:26 PM   #6  
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Oh yeah. Thanks for that note about signal to noise ratio. I haven't thought about that. I am a satellite veteran and an OTA newbie. Signal to noise usually isn't a factor with residential satellite so I don't check it very often. I'll make sure to keep that in mind with my future installs.
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Old 03-16-2014, 02:28 PM   #7  
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Default Software Defined Radio Spectrum Analyzer Calibration

The RTL2832U + R820T DVB-T USB tuner card uses a voltage-controlled oscillator (VCO) tuned by a phase locked loop (PLL) to synthesize all the frequencies required to cover its wide operating range. A phase locked loop is a feedback control system that compares the phases of two input signals to keep the VCO oscillations on frequency.

One of the two input signals comes from the VCO itself. The VCO output frequency is fed through a frequency divider back to one input of the PLL, producing a negative feedback loop. If the output frequency drifts, the resulting phase error signal will increase, driving the VCO frequency in the opposite direction, reducing the error. Thus the output of the PLL’s VCO is locked to the second input. Of course changing the divide-by count will also produce a phase error resulting in the VCO tuning to a new frequency. It is the divide-by count of this frequency divider that we change when we tune the VCO to a different frequency.

The second of the two input signals, called the phase lock loop (PLL) master clock, is derived from a very stable crystal reference oscillator that runs at ~28.8 MHz. Crystals are typically manufactured to precise tolerances and exhibit very modest temperature sensitivity. In applications where accuracy and stability are paramount external circuitry is provided to precisely align or “pull” the crystal to the desired frequency and the crystal is housed in a temperature controlled oven. Unfortunately, this adds considerably to manufacturing cost. As I said in a previous post, most mass produced dongles, while more than accurate enough for their intended purpose, will exhibit a small frequency error. This is due to the crystal reference oscillator that is supposed to run at ~28.8 MHz being slightly off frequency. Almost every RTL-SDR dongle will exhibit a small frequency error because they are cheaply mass produced and not tested for accuracy. Fortunately, this frequency error is essentially linear across the spectrum, and can be adjusted in most SDR programs by entering a “PPM” (parts per million) correction value.

When we align our individual dongles, we want to account for both the crystals frequency error and temperature sensitivity. Therefore, allow the dongle to come up to operating temperature for 10-15 minutes before starting the procedure.

RTLSDR Scanner Calibration

RTLSDR Scanner has a built-in “Auto Calibration” feature that seems to work very well against known signal frequencies. Suitable choices, since we are typically interested in ATSC TV stations, are the pilot carriers they broadcast and in most US areas, NOAA Weather Radio stations.

If your dongle hasn’t been powered on very long open the RTLSDR Scanner application and set the “Start frequency” to 162 MHz and the “Stop frequency” to 163 MHz. Set the Mode to Continuous and click “Start”. You’ll probably notice the measured frequency changing as the dongle warms up. Once the measured frequency stabilizes, you’re ready to start calibration. Note; you may have to increase the gain setting for signals to display.

Pilot Carrier Method:
Standard ATSC TV pilot carriers are 310 kHz (.31 MHz) above the channels lower band edge. Note; the exact pilot carrier frequency used by some stations may vary because the transmitted signal may be offset slightly to reduce interference. If you calibrate against a single TV station it’s a good idea to check your ppm result against other TV stations and/or one of the NOAA Weather stations.

To use a TV stations pilot carrier, pick a TV station broadcasting in your area and add 310 kHz to its lower band edge. TV Fool for your area can be consulted to determine the “real” RF frequency for the “Virtual” channel numbers you’re probably most familiar with.


A reference that lists standard RF channel & pilot carrier frequencies can be found here:


Remember to use the stations “real” RF frequency and not its “Virtual” channel number’s frequency.

Start RTLSDR Scanner. From the ‘Tools’ menu, select “Auto Calibration…”. Enter the pilot carrier frequency and click “Calibrate”. I calibrated mine on RF channel 38 614-620 MHz so I used 614.310 MHz. Ignore the reported RF frequency as it was derived prior to calculating the required ppm value to correct to the referenced pilot frequency. The “Auto Calibration” window displays the calculated (ppm) correction value and automatically enters it when you click on “OK”. You can open “Edit>Preferences…” to see the ppm value in use at any time later. Mine was 73.825.

Initiate a new scan to see how accurately your dongle reports the pilot carrier frequency. Mine reported 614.309997 MHz so it got within 3 Hz of being dead-nuts on.

As an academic exercise, I ran the “Auto Calibration…” procedure against all of my received channels and found 7 examples of broadcasters using Pilot carrier offsets. For example RF channel 18 is in use by KSCI (18.1-9 in LA) & KUSI (51.1 in San Diego)

Calibration results:
Ch. 7 = 75.297 (LA)
Ch. 8 = 75.499 (San Diego)
Ch. 9 = 75.689 (LA)
Ch. 10 = 75.866 (San Diego)
Ch. 11 = 76.033 (LA)
Ch. 13 = 74.016 (LA)
Ch. 18 = 35.442 (18.1 LA) 494.328530 MHz offset +18,533 kHz
Ch. 18 = 74.955 866 (51.1 San Diego) 494.309997

Ch. 19 = 74.056 (San Diego)
Ch. 22 = 74.310 (57.1 Tijuana)
Ch. 23 = 74.391 (31.1 Twentynine Palms)
Ch. 23 = 74.391 (6.1 Tijuana)
Ch. 24 = 74.470
Ch. 25 = 72.726
Ch. 26 = 74.623
Ch. 28 = 39.534 (28.1 LA)
Ch. 28 = 74.769 (28.1 Tijuana)
Ch. 29 = 39.982 (46.1 LA)
Ch. 29 = 73.969 (29.1 Tijuana)
Ch. 30 = 74.047 (San Diego)
Ch. 31 = 74.124
Ch. 32 = 74.199
Ch. 33 = 74.273
Ch. 34 = 73.518
Ch. 35 = 74.416
Ch. 36 = 74.485
Ch. 38 = 73.825
Ch. 39 = 73.898
Ch. 40 = 42.785 (45.1 LA)
Note: Channel 45.1 not on the air. San Diego pilot observed ~20 dB down)
Ch. 40 = 42.785 (39.1 San Diego)
Ch. 41 = 43.152
Ch. 42 = 74.109
Ch. 43 = 74.177
Ch. 44 = 74.243
Ch. 48 = 73.049
Ch. 49 = 31.494 (57.1 LA)
Ch. 50 = 73.906
Ch. 51 = 73.971

Available in most US areas, the NOAA Weather Radio service provides suitable calibration signals on one or more of the following frequencies:
162.400 MHz
162.425 MHz
162.450 MHz
162.475 MHz
162.500 MHz = 75.115
162.525 MHz
162.550 MHz
You need to determine the strongest one in your area to use one of these.

Last edited by Pete Higgins; 03-16-2014 at 02:47 PM..
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Old 03-17-2014, 05:21 AM   #8  
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Originally Posted by schamberlin View Post
Assuming I had a cheap notebook computer could this work to point antennas or should I get the Digiair Pro 2? I used a cheap $150 notebook computer to point wireless internet antennas before.
I think you would find a HDHomeRun a better tool for pointing your antenna. Plug the small device into your coax and wired network then use a laptop, tablet, or phone to look at two tuners concurrently. I paid $50 for a HDHRUS and will buy a second at next opportunity (four channels concurrently).

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Old 04-04-2014, 04:07 PM   #9  
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Default RTL2832U + R820T DVB-T USB Tuner Card Hints & Kinks

A new version of RTLSDR Scanner was released on April 2nd. It can be found here:

I finally have all three of my dongles up and running. The first one requires a ppm calibration value of 74.954, the second one 59.508 and the third one is surprisingly close @ 24.038.

Install 32 bit Microsoft Visual C++ for RTLSDR Scanner
I ran into a problem getting the RTLSDR Scanner software to work with Windows 7 following a fresh install. After countless reinstalls, I discovered that I needed to install the 32 bit version of “Microsoft Visual C++ Redistributable (x86) {vcredist_x86.exe}”. The software author actually suggested installing Microsoft Visual C++ but since all my Windows 7 computers are 64 bit I was installing the 64 bit version and that didn’t seem to work. Three computers with fresh installs of Windows 7 setup flawlessly by first installing the Microsoft Visual C++ Redistributable (x86). It can be downloaded @ no charge from Microsoft here:

To install SDR# for use with the RTL2832U + R820T DVB-T USB Tuner Card, go to the section titled “Important note for RTL-SDR users” and use the installation script provided in this section.
Unzip “sdr-install.zip” and double click on the “install.bat” file. I suggest moving the sdr-install folder and its 3 files to C:\. The SDR# application and all of its files will then be found @ C:\sdr-install\sdrsharp\. Apparently, these dongles require a lot more support than some of the other software defined radios. The stable release only contains 20 files and the release installed for my dongle has 32.

While we’re talking about SDR#, as I said in a previous post, it also lets you store frequencies (in groups) for later recall. Creating groups and entering a large number of frequencies can become quite tedious. Fortunately, SDR# saves all of your work in an XML file named “frequencies.xml” that is portable. If you plan to use your dongle on multiple computers or like me have multiple dongles, once created, you can just copy “frequencies.xml” to the sdrsharp folder and the new install will use the file over without having to recreate it.

Make your own MCX to ‘F’ cable
The 5 13/16” antenna’s that come with the RTL2832U + R820T DVB-T USB tuner cards aren’t very useful. If you have outside antennas you’ll get a lot better broad-band reception from those than you will from the little indoor antenna supplied. I decided to sacrifice one of my antennas to see if I could make a workable MCX to ‘F’ adapter cable.

I cut the coax near the base of the antenna and stripped back about ½” of the outer jacket. I separated the braid into two “ears” and striped 1/8” from the center conductor. I put a piece of heat shrink tubing on the center conductor and soldered it to the center terminal of a Panel mount F-81 connector. After shrinking the heat shrink, I soldered the ears to the edges of the F-81 as shown below:

Hint; grind or file the connector’s plating away for a better solder bond.

Not as pretty as my store bought cables, but in actual use I couldn’t tell any performance difference between the one I made and the store bought ones.
The type of F-81 I used can be found here:

If you’re throwing away an old TV or VCR, you might even be able to scavenge one.

Adjusting where the Noise Floor displays
The RTLSDR Scanner & SDR# vertical or Y axis (amplitude) are labeled with dB, not dBm, and within the same program the dB readings are relative to each other, not absolute with respect to the Y axis. The RTL2832U Analog to Digital Converter (ADC) outputs 8-bit I/Q-samples which results in about 48 – 50 dB of dynamic range. Both programs spectrum displays default to a 0 dB to -50 dB display range making the noise floor appear at about -50 dB. In order to display the noise floor closer to reality, I used the “Idle” editor that comes with Python 2.7 to edit the following files (Note; The programs SHOULD NOT be running when you do this):

Open RTLSDR Scanner’s “scan.py” file with Idle. In Windows 7 the “scan.py” file can be found @ C:\Program Files (x86)\RTLSDR Scanner\scan.py. In XP it’s located @ C:\Program Files\RTLSDR Scanner\scan.py

In RTLSDR Scanner’s “scan.py” file I changed the line that reads “power = 10 * math.log10(scan[freq])” to “power = 10 * math.log10(scan[freq]) – 51.5”. This moved the displayed noise floor down to -100 dB.

In order to display the noise floor closer to reality, in SDR#, edit the SDRSharp.exe.Config file. Wherever you put the sdr-install directory before you ran install.bat, you’ll find SDRSharp.exe.Config in the sdrsharp folder right under it. Set Idle to display all files and go to where you installed SDR#. I changed the value -40.0 in the line near the top of SDRSharp.exe.Config that reads <add key="fftOffset"value ="-40.0" to <add key="fftOffset"value ="-80.0" to move the displayed noise floor down to ~-100 dB.

I don’t want to mislead anyone into thinking that this somehow improves the sensitivity of your dongle –it doesn’t. These dongles have excellent sensitivity and have been measured down to -134 dBm. Think of the display as a window into the spectrum that is ~50 dB tall. All we did was slide the window down so the ‘Y’ axis arbitrarily says -100 dB instead of -50 dB next to the noise floor. Also, be aware that changing the filter bandwidth and/or sampling rate used will also affect the noise floor.

As was stated above, these devices output unsigned 8 bit I/Q samples at ~2.8 MS/s making the dynamic range about 50 dB. This remains essentially true regardless of the RF Gain setting. However, when one or more signals get larger than what can be handled by the A/D converter you will produce sampling artifacts and IMD products. Lowering the gain to bring the strong signals back into the A/D converters dynamic range seems to solve this at the expense of demodulating weaker signals. Intermodulation also occurs if several strong signals are present within the bandwidth of the dongle. Their individual powers are additive. Therefore, if multiple strong signals are present the gain might need to be reduced even further.
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Old 05-02-2014, 01:30 PM   #10  
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Default Channel Plus NF-471 Notch Filter

Until recently, I was only able to qualitatively access changes to my OTA configuration. With this amazing device and “RTLSDR Scanner ” I am now able to better characterize the effect system changes produce.

I live in a deep fringe area with all the Los Angeles TV stations arriving via 1 & 2 Edge paths. In line with them I have a 99.9 MHz FM transmitter @ -13.4 dBm and a -15.6 dBm PBS station about 3.5 miles from my house. When I initially configured my OTA system I experienced severe overload to my Winegard AP-2870 & HDP-269 amplifiers. I bought a Channel Plus NF-471 Notch Filter to eliminate the UHF overload caused by KVCR on RF channel 26. While it’s specified to remove channels 24 – 29, and accomplished its purpose, I noticed considerable degradation between channels 19 & 32. Below please find my attempt to characterize the frequency response of these filters.

The blue sweep represents the frequency response of an unfiltered scan between 470 & 700 MHz (Channels 14-51). The Green sweep represents the frequency response with the filter inline. As can be seen in the graphic above the filter rolls off slowly enough to also degrade channels 19 and channels 28-32. The loss to RF channel 31 was enough to make the difference between watching the “CW” and having it pixelate.


A full 470 – 700 MHz scan takes almost 7 minutes (6 min. 52 sec.) to complete. When you add in the time to climb up on the roof, make changes and complete another scan, a good 20 – 30 minutes can elapse. 1 & 2-Edge propagation over this amount of time can yield amplitude variations not directly attributable to the filter. To mitigate this I ran two filter sweeps, one before the non-filter test and one after and compared the difference. Fortunately both sweeps appeared to be within <1 dB of each other.
Attached Images
File Type: jpg NF-471 Filter Plot.jpg (47.3 KB, 21 views)
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Old 04-03-2015, 08:51 PM   #11  
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Default New Zidag USB driver installer

I just noticed that there is an update to the Zidag USB driver installer. The version available when I started this thread was “zadig_2.1.0“ and the new version is “zadig_2.1.1”.

(If you are using Windows XP, you need to download the Zidag version for XP.)

A Zidag usage guide is available @ this link:
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Old 11-06-2016, 04:04 PM   #12  
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Default RTL/SDR Update

It’s been over two years since I started this thread and a lot has changed in the world of software defined radio.

The inexpensive dongles (~$7.30 US delivered) are still widely available on eBay from China but the R820T tuners have been improved and the better ones are now sold as R820T2’s. I bought one and it does appear to have better sensitivity than my older units. FM radio stations that my Hauppauge HVR-1800 tuners won’t even pickup, these little USB dongles are able to receive crystal clear in stereo. I split the signal to each so the signal quality/strength remains equal.



I started with the dongles that use an MCX connector for the antenna input and ordered premade MCX to ‘F’ female cables to easily interface with my TV antenna’s RG-6 feeds. (~$1.84 to $1.98 US delivered)


http://www.ebay.com/itm/DHT-Electronics-RF-Coaxial-Coax-Cable-Assembly-MCX-Male-to-F-Female-6-inch-/322231912991?hash=item4b0684ca1f:guoAAOSwMtxXtSz 1

The Right Angle Adapters are handy in tight spaces:


To interface with HAM antennas you can also get Right Angle MCX Male Plug to SO-239 UHF Female Jacks with a 6 in RG-316 Pigtail for as little as $2.39 delivered:


Of course, you can get solid adapters but I find that the short cables act as strain relief’s and keep the heavier RG-6 from dislodging the USB dongles.

One other thing I should mention, while we’re on hardware, is that I have 4 computers connected through a KVM-A switch (with 3 USB) ports in my office. I connected a 7 port USB hub to one of the KVM switch’s USB ports and plugged one of the RTL2832U + R820T2’s dongles into the USB hub. This way, I’m effectively able to share one dongle between four separate computers.


In order to communicate with the RTL2832U + R820T2 dongle you need to install generic USB drivers. Zadig is a Windows application that does that. (Note; You need to download the correct version of Zadig for either Windows XP or Windows Vista & higher) The latest version of Zadig is 2.2.

In Zadig, go to Options and make sure “List All Devices” is checked.
Select “Bulk-In, Interface (Interface 0)”, “RTL2832UHIDIR” or “RTL2832U”, whichever shows up with your dongle plugged in.
Ensure that the driver on the right hand side of the green arrow is selected as WinUSB
Click the Replace or Reinstall Driver Button

Link to download Zadig:

Link to Zadig 2.0 - User Guide:

SDR Sharp (SDR#)

SDR# is the program I use 98% of the time. This program allows me to tune and listen to the full frequency range of the RTL2832U + R820T2 dongle and even supports listening to FM stations in stereo. I often play background music while I surf the web, read email or work. As of this writing the latest 64-Bit version is The last 32-Bit version is

Link to download 32-Bit SDR# Software Package:


Link to download 64-Bit SDR# Software Package:


Link to a quick start guide to get your dongle & SDR# up & running:


Basically, once Zadig has installed the WIN USB driver all you need to do is download and unzip sdrsharp.zip to a folder on your PC. I typically unzip it in my “downloads” directory and then move the unzipped sdrsharp folder to C:\ so it’s easy to find. Once you have it in its permanent location double click on the “install-rtlsdr.bat” file. This will start a command prompt that will download the remaining drivers required to make SDR Sharp work.

RTLSDR Scanner has an automated feature to determine the frequency correction for individual dongles so I usually use that and come back to enter the derived value into SDR#. If you’re not installing RTLSDR Scanner you can get close by tuning to a known narrow band FM signal and adjusting the correction for best sound. (I like to use WX Band signals @ 162.400, 162.425, 162.450, 162.475, 162.500, 162.525 or 162.550) Tune (click the top or bottom of each number in the frequency display to set it to the channel that looks strongest on the spectrum analyzer display. Click the gear icon at the top of the display & use the Frequency correction (ppm) arrows to run the number up to where the tuned channel sounds best. My dongles require a low of 19 ppm to a high of 75 ppm.


SDR# has an active spectrum analyzer display that displays a ~2 MHz portion of the spectrum which is limited by the bandwidth of the dongle (For example 88 MHz to 90 MHz). RTLSDR Scanner progressively scans from a user defined lower frequency limit up to a user defined upper frequency limit then stitches the entire scan range into a conventional spectrum analyzer display (For example 88 MHz to 108 MHz or 470 MHz to 700 MHz). It looks at each segment for 131 ms by default. RTLSDR Scanner has proven invaluable to be able to view the channels received at my location and their relative signal strengths. It is capable of loading two saved scans to compare the effect of different antenna configurations.

The author has traditionally used a script based install that from my experience was occasionally prone to failure. He recently released standalone versions of the application that while a little more involved to initially configure seem to be bulletproof and portable from one computer to another when configured.

Link to download RTLSDR-Scanner:


(Note; for 32 Bit version (i.e. XP, Win 7 & 10 32-Bit, etc.) scroll down the page)

1. Plug RTL2832U + R820T2’s dongle into a USB port or hub.
2. Run Zadig to install the WIN USB driver (If you’ve already installed SDR# this step isn’t necessary).
3. Download the RTLSDR-Scanner executable file.
4. Make a RTLSDR-Scanner directory & copy the RTLSDR-Scanner executable file to it.
5. Download & copy the RTLSDR libraries to the RTLSDR-Scanner directory.
6. Optionally, download & copy msvcr100.dll to the RTLSDR-Scanner directory.
7. For the 64-Bit RTLSDR-Scanner executable download & install Visual C++ Redistributable Packages for Visual Studio 2010 (x64) or 2013 (x64).

The latest standalone 64-bit release of “rtlsdr_scan-windows-64bit.exe” is v1.0.22497.10311 released on Sep 20, 2016

The latest standalone 32-bit release of “rtlsdr_scan-windows-32bit.exe” is v1.0.22180.60082 released on Jan 28, 2016

These are both Windows executable files that require additional support libraries to function.
I suggest creating a directory (folder) labeled “RTLSDR Scanner 32 Bit Stand Alone v1.0.22180.60082 Released on 28 Jan 2016” and copying “rtlsdr_scan-windows-32bit.exe” into it.
For the 64-Bit executable create a directory “RTLSDR Scanner 64 Bit Stand Alone v1.0.22497.10311 Released on 20 Sep 2016” and copy “rtlsdr_scan-windows-64bit.exe” into it.
The 64-Bit RTLSDR-Scanner executable requires you to install Visual C++ Redistributable Packages for Visual Studio 2010 (x64). or Visual C++ Redistributable Packages for Visual Studio 2013 (x64).

Both the 32-Bit and the 64-Bit versions require you to download the RTLSDR libraries and utilities from Osmocom named “RelWithDebInfo”.

Link to download RelWithDebInfo:


Download and unzip RelWithDebInfo.zip to a folder on your PC. It will create a directory named “rtl-sdr-release”. When you open that directory, you will see folders labeled x32 & x64. You need to copy the following files into the directory that contains the RTLSDR-Scanner executable file so it ends up looking like this:

pthreadVC2-w32.dll or pthreadVC2-w64.dll
rtlsdr_scan-windows-32bit.exe or rtlsdr_scan-windows-64bit.exe

Notice that except for “pthreadVC2-w32.dll” or “pthreadVC2-w64.dll” and the RTLSDR-Scanner executable all the RTLSDR library files have the same name but are different file sizes. You must copy the files from the correct x32 or x64 directory depending on which version of RTLSDR-Scanner you are setting up.


The correct version may already be on your system – or maybe not.

Both the 32 & 64-Bit versions of RTLSDR-Scanner require msvcr100.dll. Like the RTLSDR libraries, msvcr100.dll comes in 32 & 64-Bit versions. The 32 bit version is incompatible with the 64 bit one.

The 32-Bit version of msvcr100.dll is 756 KB (It comes with SDR# if you need it or can be found in the Windows 10 Professional Windows\SysWOW directory)

The 64-Bit version of msvcr100.dll is 810 KB (I just copied it from the Windows 10 Professional Windows\System32 directory)

To make your RTLSDR-Scanner setup portable, I recommend downloading the correct 32 or 64-Bit version and including it in the directory with the RTLSDR-Scanner executable file.

Many programs depend on msvcr100.dll and usually install it in their application directory, or C:\Windows\System32 and/or C:\Windows\SysWOW64. My 64-Bit Windows 7 & 10 Professional installations had the correct 64-Bit version installed. However, Windows 7 Home Premium 64-Bit and Windows 10 Home 64-Bit did not. Also, when I did a fresh install of Windows XP Media Center Edition the 32-Bit msvcr100.dll was not installed. Windows will first look in the application directory and then in all the directories in the path statement to find msvcr100.dll. If you overwrite a 32-Bit version with a 64-Bit version or vice-versa you may break other applications. That’s why I recommend including the appropriate msvcr100.dll file in the directory with the RTLSDR-Scanner executable file.

Finally, if your installing the 64-Bit RTLSDR-Scanner executable download & install Visual C++ Redistributable Packages for Visual Studio 2010 (x64) or 2013 (x64).

Link to download RTLSDR-Scanner & the Visual C++ Redistributable Packages:


I noticed that the Stand Alone versions take longer to load than the older versions installed by the script method. When I queried the author (Al) he replied “The stand alone application takes longer to start up as it extracts files to a temporary directory first when you run it. It's quite normal and nothing to be concerned about”.
Attached Images
File Type: jpg Zadig.jpg (43.6 KB, 6 views)

Last edited by Pete Higgins; 11-06-2016 at 10:30 PM..
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Old 12-04-2016, 10:56 PM   #13  
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Join Date: May 2016
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Posts: 108
Default RTL SDR scanner

I want to give a shoutout to Pete Higgins!

Here is a guy who really gets into what he does. I read this thread a year or so ago and had some interest, but didn't take the time to do much with it.
Recently, when Pete updated this thread, it re-peaked my interest and I ordered the dongle, the Coax adapter through E-bay installed the RTL software
and I am extremely satisfied with my set-up exactly as described by Pete Higgins. I admit, I had some help from Pete, who was gracious enough to take
some time out and trade e-mails and a couple of calls.

It wasn't that hard, I just got a little confused on some of the steps, which Pete had laid out already, I just didn't read it carefully.
But hey, I am glad that I did this. And, thank you Pete!

I wanted a way to measure my changes to my system but could not justify an expensive analyzer.
I just tee in my dongle and coax adapter via splitter to whichever array I want and I can see what my effects my changes can have.

One of the things was to eliminate a couple of splitters that were in place only because I didn't redo my basement cable routing under the upper floor when I should have after eliminating some cables to rooms I didn't use a TV in anymore. After redoing my cables and eliminating those extra splitters I picked up several db of signal strength.

Also aiming the antennas was another use for the spectrum analyzer. This software is excellent!

Some sample screenshots:

Milwaukee with all splitters:

Milwaukee with no splitters:

Full spectrum Milwaukee and Chicago antennas combined:

One thing about the spectrum analyzer, it is true it is slow and even seems to be locked up, even on my WIN10 Pro i7 4770 w 16 GB RAM,
it stalls out and the little blue Windows circle just spins, but no worries, it does complete the task in several minutes.
I just wait and do another task, like a forum post because it does not lock up the PC, just the program.

UHF Antenna pointed at Chicago channels 28-51 ANNOTATED ALL SPLTTERS USED.jpg

UHF Antennas combined channels full spectrum annotated splitters and combiners used.jpg

UHF Antenna pointed at Milwaukee channels 18-51 ANNOTATED ALL SPLTTERS USED.jpg

UHF Antenna pointed at Milwaukee channels 18-51 ANNOTATED NO SPLTTERS USED.jpg

UHF Antennas combined Chicago&Milwaukee channels full spectrum annotated splitters and combiners.jpg

Last edited by Chiwaukee OTA; 12-04-2016 at 11:18 PM..
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Old 12-05-2016, 02:28 PM   #14  
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Location: California, 58 miles @112 degrees from Mt. Wilson
Posts: 265
Default Inexpensive Software Defined Radio Spectrum Analyzer < $10.00

Thanks for the kind words Bob.

One of the really handy features of RTL/SDR Scanner, that we didn't get to talk about, is its ability to compare two scans. For example, if you do a scan of the FM band with the FM filter on your RCA TVPRAMP1R Amplifier switched off and save it. {File>Save As…>”FM Trap Off Scan 88.0-108.0MHz.rfs”} and then do a scan with the trap switched in {File>Save As…>”FM Trap On Scan 88.0-108.0MHz.rfs” you can load both scans into the application and compare the difference the trap makes. {Tools>Compare…}. When the “Level Comparison” screen opens, load Plot 1 (blue) & Plot 2 (green) and it will show you the attenuation applied by the filter. If you cursor over a signal frequency it will show you the signal strength @ that frequency for both plot 1, plot 2 & the difference in signal strengths between the two plots.


If you check the “Difference” check box it will plot the difference between the two scans in red.


You can also save out the “Level Comparison” screen in a number of graphic file formats.

Last edited by Pete Higgins; 12-05-2016 at 05:26 PM.. Reason: Add Google Drive Links
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Old 12-06-2016, 06:14 AM   #15  
"Gaining" OTA Knowledge

Join Date: May 2016
Location: Beach Park IL
Posts: 108

Hi Pete, you are welcome.

That difference feature looks pretty handy. As I was re-cabling my coax cables, shortening many of them, (in the past I had no way to make or shorten cables) and eliminating splitters, I made scans and watched the signals strengthen and at one point going direct from the antenna down lead direct to RTLSDR.

I saved most of the scans, maybe I can try that out.

Stay tuned
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