SDR# General question on receiving

[MrBungle]

I have a V4 RTL dongle, and I need to ask this question.

Receiving is terrible. For example, I can pull in data channels, I can decode Inmarsat, and I do a lot of pager decoding- so much interesting stuff still on pagers in the 929/930Mhz region.... But when I want to tune to a simple frequency like 155.595Mhz, I get nothing. Nothing ever shows, no activity, just crickets on that (and other) frequencies. It's a simple non digital analog transmission. I can't listen to anything thats not data related.

What am I missing? I have an RTL LNA attached also that I use- but if it's an analog signal? There's zero chance I can pick it up.

 

[Reconrider]

You will only see analog signal, when you get analog signal aka when they talk.

Try turning off "correct IQ" and "Invert Spectrum". Not sure why those are on - pretty sure those are unneeded in analog

 

[MrBungle]

You will only see analog signal, when you get analog signal aka when they talk.

Try turning off "correct IQ" and "Invert Spectrum". Not sure why those are on - pretty sure those are unneeded in analog

Thanks for the reply. I get the analog thing, I'm no stranger to scanners. I've had those changed, makes no diff. Super frusterating for sure.

 

[paulears]

The thing tha5 surprised me is no spike on 156.0? In marine band, that frequency is plagued with switch mode power supply interference. All my receivers, not just SDRs seem to hear it, including the Icom marine radio in the van as I drive past houses. It is often internet hun psu’s i note! marine band in my harbour is quite busy, and at least three times a day HM Coastguard do long broadcasts. You dont hear any of this at all? How about in the 153 range? I have some mega strong spikes there From pager systems.
EDIT, sorry just realised you are in the US, not UK. UTAH on my map is not near the sea? The map says you have other states surrounding you? 156 up is marine so will be empty. What is in your 155 band you cant hear? What about hams and their repeaters a bit lower?

 

[N1EXA]

Antenna ?
Get it far away from the Computer !

Pete N1EXA

 

[Reconrider]

Thanks for the reply. I get the analog thing, I'm no stranger to scanners. I've had those changed, makes no diff. Super frusterating for sure.

Can you test the signal on your NOAA channel and see if you get anything? Test it on a radio station that you have no issues picking up. If you get no audio / no signal, I would say your antenna is in the absolute worst place(antenna near metal/RF noisy computer) or you need to reflash the driver with zadig.exe again

 

[prcguy]

The metal computer case is going to degrade reception with antennas attached to it not to mention computers are huge RFI generators and your noise floor will be huge, covering up many stations. Get a real antenna and move it far away from the computer and close to a window or get it outside. I would also loose the LNA, it will not make up for antenna gain and will add more noise to the system. An LNA can be ok for feeding a long run of coax but not needed in most cases.

 

[dave3825]

Your gain is maxed out at 49.5dB and your using an LNA. Too much gain can drown out signals, amongst other things.




Not sure a Y splitter is the best choice for running 2 dongles off an LNA on one antenna. I had reception issues that went away the minute I started using a multicoupler which isolates each port. .





Antenna is a major factor and yours seems to have 2 issues. Your dipole is right up against your laptop.

And for 155mhz, one leg should be close to 3 feet extended and the other 18 inches extended.




Yours looks like its tuned more for 900 to 1 ghz.



.

 

[pb_lonny]

Aerial type and placement would be the major issue.

 

[prcguy]

View attachment 171206

Your gain is maxed out at 49.5dB and your using an LNA. Too much gain can drown out signals, amongst other things.




Not sure a Y splitter is the best choice for running 2 dongles off an LNA on one antenna. I had reception issues that went away the minute I started using a multicoupler which isolates each port. .


View attachment 171207


Antenna is a major factor and yours seems to have 2 issues. Your dipole is right up against your laptop.

And for 155mhz, one leg should be close to 3 feet extended and the other 18 inches extended.

View attachment 171214


Yours looks like its tuned more for 900 to 1 ghz.



.

Both elements should be around 18”, 36” would be total length for both.

 

[MrBungle]

Wow everyone, thanks for all of the really good info. I'm going to go through these recommendations and impliment them, will report back.

 

[paulears]

Side question. I just bought the rtl dongle top in the pic and it gets hot! Is this normal?

 

[morfis]

... it gets hot! Is this normal?

In my experience, yes.

 

[paulears]

Aha! That's good to know. If it gets hot, then my laptop might struggle with it's knackered battery!

 

[MrBungle]

Aerial type and placement would be the maj

Thanks- I've got a couple of other antenna options available, I'm trying them now

Aerial type and placement would be the major issue.

Ya, you right. I removed it.

Antenna ?
Get it far away from the Computer !

Pete N1EXA

Thanks- I've done that. I have it on a simple tripod.

Can you test the signal on your NOAA channel and see if you get anything? Test it on a radio station that you have no issues picking up. If you get no audio / no signal, I would say your antenna is in the absolute worst place(antenna near metal/RF noisy computer) or you need to reflash the driver with zadig.exe again

Thanks- so I'm checking my NOAA now. My local area should be 162.400. I changed to in in SDR and nothing. I got out my trusty old Radio Shack Pro-93 and manually tuned. Not hearing them. Guess it's not so trusty anymore.

I used CHIRP and loaded all of them into my little TID H3. I got NOAA on 162.400.

Your gain is maxed out at 49.5dB and your using an LNA. Too much gain can drown out signals, amongst other things.

Not sure a Y splitter is the best choice for running 2 dongles off an LNA on one antenna. I had reception issues that went away the minute I started using a multicoupler which isolates each port. .

Antenna is a major factor and yours seems to have 2 issues. Your dipole is right up against your laptop.

And for 155mhz, one leg should be close to 3 feet extended and the other 18 inches extended.

Yours looks like its tuned more for 900 to 1 ghz.

Great callouts. I've been using the 800/900 region a lot lately (trying to get SDR Trunk working- another collosal failure) and I have the longer antenna that comes with the dipole kit. I have a car antenna on a small tripod I've been using.

So all I have is a USB extension cable, V4, then my antenna. I'm not getting anything but my strong pager frequencies, and I also made a sat antenna and recieve JAERO quite consistently. That and ScytaleC works good too, I can get a good lock.

Anything UHF and I'm not very successful. No conventional FM either.

The JAERO antenna is special, with it's own antenna wiring, so right now I'm leaning towards my antenna as a whole. I'm going to order a new one. Pager frequencies are powerful enough to blast through anything, also.

 

[sunwave]

@MrBungle RTL-SDR's are very noisy at high RF Gain. If using a LNA you don't need much gain. If your LNA specs says it has 20dbm gain then don't go past +25 on the RF Gain. For that to work is to never ever mount antennas on a laptop, monitor, pc chasis at all. Get that antenna at least 10 ft away mounted on a tripod or some other method of mounting. You may just start seeing signals.

 

[MrBungle]

Well, here's what I've done.

Put the V4 on a USB extension, then attached the dipole. The antenna is maybe 4 inches away from the V4, then 6 feet of USB. Thats it. That simple path is getting me zero results.

Ttried the Nooelec, same thing. I get zero, zero, zero conventional recieving on this. All I can use it for is JAERO and paging in 900 and thats it.

I've had a scanner in my hand since 1990, and been lurking around this site since 2002. But I'm apparently too dumb to figure this out.

Thanks anyways everyone for your time. I'm not wasting any more time on this. I've spent months and months with different antennas, configurations, cables, everything. I've spent close to $200 in an attempt to listen to one single frequency. It's been a collosial waste of time and money for 155.595 on my computer. I'm actually shocked at how much time and money I've wasted.

 

[MrBungle]

Ill stick to data eavesdropping instead.