|Topic Review (Newest First)|
|2019-09-13 11:27 AM|
Using SDRsharp for Noise Interference Measurements
SDRsharp can also be used to look for noise. It can't show all of VHF-High at once, but it can show part of a channel and the adjacent noise. This is my channel 7:
a closer look:
My channel 9 is much weaker; it's marginal and can't always be received.
The signal is weaker than -45 dB, and is less than 15 dB above the noise floor; not enough SNR.
One nice thing about the spectrum analyzer is that it tells you if the channel is there. If you do a channel scan with your TV tuner and it doesn't pick up a channel, you don't know if the channel is there or not. The spectrum analyzer answers that question.
|2019-09-13 11:20 AM|
Originally Posted by lenlab
Originally Posted by lenlab
|2019-09-11 11:21 AM|
Try setting the gain at 25 dB. Click on View > Preferences > set gain to 25 dB > click OK
Try it first without the amp, then with the amp.
|2019-09-11 09:52 AM|
I bought the same dongle. As I said I have it working on my win10 desktop with SDR# (haven't tried other software) and my 2 old laptops with XP and Linux and various software.
On my Dell XP laptop I have installed the simple RTL Scanner and ran it with my antenna feed to get a scan of my VHF spectrum. As soon as I can I will show the results on this forum and elsewhere.
11.1 = 199.25
13.1 = 204.25
|2019-09-10 02:55 PM|
It was new to me also, so it took me many attempts to get it working. I selected the RTLSDR-Scanner software for the spectrum analyzer. SDR# and similar software is fun to use, but the dongle MHz bandwidth is too narrow to scan VHF-High. A spectrum analyzer program stitches together segments to cover the band.
Channels shown above are 7, 9, and 13. Channel 9 (the middle channel) is marginal, it doesn't always have enough SNR to be 15 dB or more above the noise.
Simple earlier version; wait for popup (see Pete's post #47 on other forum)
if no popup
v1.0.22180.60082 next page
64 Bit v1.3.0 RTLSDR Scanner v1.3.0 (Pete's post #56 on other forum, not for XP)
|2019-09-10 10:27 AM|
An Update on my journey and experience. I bought an RTL-SDR USB device and then tried out software to get it working.
One caveat is I have no clue what I am doing and what the resulting displays are showing me with the various software discussed:
SDR# I loaded on my Win10 desktop with no issues and it seems to be working well. I can tune to various FM stations with a small portable antenna and hear them and see the results displayed. However it will be a challenge getting my antenna coax to this desktop.
SDR# loaded Ok on my old Dell Win XP Laptop but I could not get it to work. I can tune to an FM station but as soon as I try to make any changes to settings SDR# locks up and hangs the laptop. Only recourse is to power off. So it is not really working.
SDR Scanner was installed on the Dell WIN XP Laptop and it seems to be working well.
HDSDR is an application I don't see talked about here but it loaded on the Dell XP laptop and works. It seems to be a clone of SDR# as best I can tell with similar displays.
Finally I was able to download and install from the Linux repositories GQRX and have it running on my old Lenova laptop.
So there is hope for making use of old equipment even though there is not much support for Win XP these days as most developers have moved on.
Now that I have three computers with software I just have to get trained somehow on what the heck the displays are showing me. Besides having the ability to listen to a radio I am interested in analyzing my high VHF OTA signal for noise interference.
|2019-08-24 03:37 PM|
Thank you for the reply. Well, that eliminates those two possibilities.
The next thing to suspect is a high noise level on VHF.
|2019-08-24 11:19 AM|
The first filter I tried was a Blonder Tongue ZHLSJ. The one I am currently using is a JVI 25-HLSJ.
Solar electric panels with micro inverters. They shut off when the sun goes down so if they were an issue I would get better VHF at night. Does not happen.
|2019-08-23 03:56 PM|
I use a portable battery operated radio tuned to a clear frequency in the AM broadcast band to hunt for noise interference:
Interference with Radio, TV and Telephone Signals
I asked you about your solar panels:
Originally Posted by rabbit73 View Post
Originally Posted by lenlab
|2019-08-23 11:58 AM|
This report is for your location:
This is an extract from that report:
You can click on Current Station Search List or Post-Repack Search List. In both cases 7 is stronger than 11.
I wonder which transmitting site are they actually using, the old ESB (Current), the new WTC (Post-Repack), or AUX and are they at full power?
If you click on Transmitter Distance in your report, a terrain profile will come up. Both signal paths are blocked by terrain, but the WTC path looks better:
|2019-08-23 10:21 AM|
Just another update.
So yesterday I put on VHF channel 7.1 and it was unwatchable as there was what appeared to be noise on the TV screen. I bought a new HLSJ a few weeks back and decided to give it a try. After I installed it VHF channel 7.1 was now almost perfect with some minor pixelation showing up from time to time.
So there must be some FM noise impacting 7.1. It was not all corrected but the filter helped a lot. Must be some noise still getting past the HLSJ.
11.1 is still a no go.
|2019-08-13 09:58 AM|
Just a brief update:
I brought my antenna feed out of the distro amp directly into my Samsung TV and it was receiving 7.1 with an SNR (Per the TV Tuner of 16-17 with a lock). The picture was solid for the most part with a rare pixelation.
However still NO to 11.1.
So I checked the same feed into my DVR+ and the results were high signal but pic quality 0. No picture.
So somehow the tuner in my Samsung TV dealt with the situation better for 7.1.
|2019-07-19 09:50 PM|
I had a similar issue with a 2 edge channel 13 signal here. That was compounded by power lines that created a lot of noise. With analog signals, interference could be seen and often diagnosed based on its appearance. I always had a watchable picture even if it did have some video noise. With digital signals there is no indication other than degraded signal quality and, depending on the tuner, sometimes not even that. That same channel, now digital and significantly weaker, often disappeared, probably due to EMI or tropo interference, and one day just disappeared. Never did figure it out. It just sat there at 70% signal strength and 0% quality unless tropo gave it a boost. I could easily see the signal on a spectrum analyzer and there was no indication of what was causing the issue.
|2019-07-19 07:33 PM|
You don't really know what's going on in the VHF spectrum, because to date you haven't looked at it. I would get working on looking at the spectrum as discussed here.
The questions you wanna answer by looking at the spectrum... what is the noise floor doing? IS the signal buried in the noise, or is the signal above the noise and still not decoding?
When my VHF yagi was in the other position, it was definitely a lack of strength.
The same move a few feet one way or the other can get you out of multipath as well in some cases.
Yes Jorgek, the eave mount install WAS a little tricky to do despite 3 people,
"me, myself and I".
|2019-07-19 08:32 AM|
Nice story. However was your problem caused by lack of signal strength, signal quality or both? I have plenty of signal but 0 quality. Seems strange that I get 100% signal strength on 13.1, 11.1 and 7.1 but 0 quality on 11.1 and 7.1 and 100% quality on 13.1.
Yes they broadcast from different locations but it's only a few degrees apart from my house.
I have 2 vhf antennas at different locations and they both have the same signal quality issue with 11.1 and 7.1. I have tried different orientations and the same results.
I continue to search for an answer. I am leaning on it is NOT FM noise but will still work on that angle. The only other thing that is fixable is maybe cell tower noise?
|This thread has more than 15 replies. Click here to review the whole thread.|