Touchstone — Rf Spectrum Analyzer Software With Dvb-t Dongle

[Babadem]

Interesting subject.

 

[mikelib]

Looks like they have algorithmic issues with the software signal processing. I can't read the scales accurately, but the spacing of the nulls looks suspiciously like the maximum sampled bandwidth of these sticks. Perhaps they didn't take the anti-aliasing filter into account, or worse. Regardless, this is obviously a work in progress.

Thanks for the reply. I went from 1 meg to 300 meg to check out the bandwidth and as the scanning bandwidth increased the baseline had more evenly spaced spikes. It's worth an e-mail to the Touchstone to see what their explanations is. When you put the analyzer in demo mode it does not show any of the artifacts, the baseline is clean.

 

[cypherstream]

Can you also use this as a simple RF level monitor for cable tv distribution systems? I understand you wouldn't be able to monitor the entire return path without an up converter, but looking to see forward equalization from 54-870 MHz, signal level and bandwidth utilization.

Any plugins to see QAM constellations (16, 32, 64 or 256) or QPSK?

 

[cypherstream]

I guess because it cannot tune a 6 MHz wide chunk of bandwidth, we won't see plugins for QAM at least for Cable TV.

It would kind of be neat, though getting hairy on ethics, to tune one of the DOCSIS channels and pipe it into Wireshark. They don't use BPI+ (Baseline Privacy) here. Or just do an entire inventory / mapping of the system by finding used QAMs, how fully utilized are they, find unused frequencies, etc.. to gauge system capacity. Love to be able to script out a program that used this to scan the whole band and write pmt, pat, or psip data to a spreadsheet.

 

[TRG]

Connected the RTLSDR USB dongle to the IF loop out port of the mini HD SE

Please excuse my ignorance but I don't see an IF loop out port on the mini HD SE.

 

[Titanium]

Please excuse my ignorance but I don't see an IF loop out port on the mini HD SE.

You are right! It must have been the 8900. Sorry! On the mini HD SE I use a 2x1 splitter with the the power blocked port connected to the DVB-T. Good catch!!!

 

[mikelib]

Does your 2x1 splitter have a low insertion Loss???

 

[Titanium]

Depending on the frequency, but probably the same or less loss than connecting via a STB loop through. If it were a more critical use spectrum analyzer, it would be directly connected. At least through a filtered splitter there is less chance of picking up noise and other rf shaping from looping through the STB.

 

[mikelib]

Thanks Brian, the new STB don't have loop through, I bought a DC blocking from WallyHTS at the Dayton Ham Fest and it had such a high loss that blocked the signal from the NBC MUX on 72 W. I have been using the Touchstone spectrum analyzer to view the transponders on satellites, but the Touchstone dose not give a very good display picture of the transponder signal.

 

[Titanium]

I find the Free version of Touchstone to be a great value!

It is nice for seeing the big picture of changes on the satellite. The spectrum trace is hard to read with the peak and current simultaneously displayed, but I find the frequency monitoring mode (Pro version $49) to be much easier to read and for giggles, I used it to align a dish last week! As good as any multi-transponder meter!

Now if this were on Android OS.....

 

[Cham]

Future app for the A3?

 

[Titanium]

I ran it on an Android STB, so it should work fine with the A3. Only needed to download a driver and the dongle was recognized.

 

[Dee_Ann]

On Brian’s recommendation I decided to see what this is about.
Found the gadget on ebay for $10 and change.




And, amazingly enough, it’s a US seller! How did that happen??

 

[spongella]

Hello all,

This is my first time on the forum. A great group of folks. Regarding the NutsAboutNets dongle spectrum analyzer, I purchased the package last year on Ebay which included the dongle and the program, cost was $79. Was well worth it. Have used it to look for OTA stations in my area that were too weak to be picked up by my TV set, this was revealing. There are other OTA TV stations out there that the dongle can detect (as per the spectra) but the TV will not display as they are too weak.

Using the dongle/spectrum analyzer is also very useful during band openings, which occur here during the warm months and usually during the morning rush hour. Most of the OTA TV DX stations over the past few years have been as far as York, Pa, as far South as Virginia, and as far North as CT. When the band is open I use the dongle analyzer to monitor the signal strength of the DX station over time.

This is a great no frills analyzer for the hobbyist. And to boot you can use the dongle as a receiver.

By the way I tried to swap the 820T dongle for one with the Elonics 4000 tuner but the spectrum analyzer program did not work.

Also, when running the program, check periodically for software updates, there has been at least one or two so far.

Spongella

 

[KE4EST]

Welcome!!!

 

[goaliebob99]

I finally was able to pickup a DVBT for like 7 bucks on amazon and gave this little guy a shot. This works amazingly awesome. No receiver is required but you do need to get power to the LNB. I am fortunate enough to have one of those 13 to 18 power inserters so I was able to get power to the LNB that way. This works very well and all you have to do is find the LBand frequency's. This even works with ATSC signals in the UHF and VHF range. Technically any signal in that freq range. I just wish that It did the full Lband sweep versus 300 mhz only, but irregardless it will get you on and you can fine tune from there. This is a very nice setup and you dont need to spend 3,000 plus on a spectrum analyzer. You cant beat the value of 7 bucks and free software to do the job.

Now, is the paid version worth it and whats the differences?

 

[spongella]

I finally was able to pickup a DVBT for like 7 bucks on amazon and gave this little guy a shot. This works amazingly awesome. No receiver is required but you do need to get power to the LNB. I am fortunate enough to have one of those 13 to 18 power inserters so I was able to get power to the LNB that way. This works very well and all you have to do is find the LBand frequency's. This even works with ATSC signals in tKkkhe UHF and VHF range. Technically any signal in that freq range. I just wish that It did the full Lband sweep versus 300 mhz only, but irregardless it will get you on and you can fine tune from there. This is a very nice setup and you dont need to spend 3,000 plus on a spectrum analyzer. You cant beat the value of 7 bucks and free software to do the job.

Now, is the paid version worth it and whats the differences?

K9SAT: Interested in your use of the spectrum analyzer for the L band; what type of antenna is used for that? Yagi, discone? Anything interesting on that band?
By the way, I never used the free version, but I have the paid version, it's great. I am doing something similar to you on the Ku band to see what the transponders look like. I can see them but don't know how to interpret them
Thanks.

Sponge (a.k.a spongella).

 

[goaliebob99]

I am using a satellite dish and LNB and using L band differently than scanning for anything open in that 1-2 ghz range through the airwaves.
L band, also referred as the IF signal is the frequency going down a coax cable, usually within the 1 - 2 Ghz range.

Example:
1. The LNB receives the downlink transponder satellite signal at 11700mhz and subtracts the LO frequency of the LNB of 10750 and outputs an IF or L band signal of 950mhz.

• DL - LO = IF (11700 - 10750 = 950)

2. The IF signal of 950mhz travels down the coax to the satellite receiver or analyzer.

More in-depth here. http://www.satelliteguys.us/xen/threads/lnb-lo-frequency-101.301707/

 

[spongella]

K9SAT,

Thanks for the reply, that makes sense. Am doing the same thing with Ku band, have a Universal LNB on a 30 inch stationary dish and can switch LO (9750 or 10600 MHz) depending on what the requirements are. Not too many Ku stations I know of that need that lower frequency LO other than some FTA stations on 45W, at least from this part of the country. Right now the dish mounted is on a wooden pallet on the ground with concrete blocks and pointed at Telstar 12, 15W.

For Telstar 12 the downlink frequency for TVGE and TPAI is 11964 MHz minus the LNB LO frequency of 10600 MHz which = 1364 MHz. With that in mind I have been scanning from 1200 - 1500 MHz using the dongle spectrum analyzer to see what appears on the scan for this satellite. So far so good. But I want to scan both vertical and horizontal polarities and also switch on/off both LO frequencies to see if there are any other hot transponders on this bird. Just for curiosity sake. I know sats transmit many different types of data, etc. Not interested what the data is, just want to see what my STB is not seeing.

Am using a Channel Master CM-1007A satellite meter to provide voltage to the LNB and have the dongle analyzer connected to the meter's output. This meter is great in that you can change the LNB voltage from 13V to 18V for polarity. Can also manually turn on a 22 KHz signal to switch LO frequency.

Sponge