etherxrally

If you have a HAM license you can transmit at much higher levels and achive long distance links. However it is not ok to send secure (encrypted) traffic on HAM frequencies. I wouldn't call this SDR because its just programming it to be out of band. If you could get the IQ samples and use software to change modulation etc then it could make things more interesting.

good call. I wonder what kind of range those would have though. Seems like it would have to be in close proximity like a apartment building or office setting.

sdr sharp has some plugins that act like a scanner. more info here....http://www.rtl-sdr.com/sdrsharp-frequency-manager-scanner-v1-31-update/

Im not sure about the e4000 sets but iirc these usb sdr sticks are using 75ohm. I think this traces back to the fact that they were used for tv which uses 75ohm coax. RG59 may be a better choice and is available at home depot etc. where RG58 (50 ohms) is a little harder to find at local shops. Specs can be found here http://www.rtl-sdr.com/about-rtl-sdr/

I dont know what is more common. Most of the time i set the decoder to decode both and didn't pay much attention to what mode was detected. I can say that the two pagers I have to have for work are FLEX. I suspect that Elfnetcommunications would know more about which is more popular and maybe will chime in with a little better idea of what we see here. I was playing around with PDW and found that there is a filter built in that I didnt see ealier. Its much like a wireshark for paging.

It could be they are way off freq. The only other thing I would suggest would be to check with other narrow band stations (you may have done this already) rather than broadcast wide band FM. The reason for this is that it is easier to find the center frequency on a narrow band channel giving better resolution. Again you may have already done this and if so you found a station way out of band, a good find if so!

If you are looking for frequencies in your area check out radioreference.com. Dont be alarmed if the frequencies are off a bit like TN.Frank said. If fact the frequencies are more than likely right on but the sdr isn't. It should be close enough to find the signal anyway.

I have found with my RTL that the auto gain is too hot. I normally set the gain manually but I am using SDR# or HDSDR. GNU radio may have similar issues. With no exposure to GNU radio I don't know if you can set it manually but if you can I would try to set it to somewhere around 30db for a start. The other option may be that the waterfall is set to sensitive and may need adjusting as well as the audio gain. I had to play around with SDR# and HDSDR to make the output worth anything. I know this isn't much help but maybe GNU radio is similar. Let me know what you find, sounds like you are close and just need a little tweaking.

If you are in the bay area you could try looking between 928 and 931 mhz and you should see some action.

What you are talking about is the First, second, third, etc.... harmonic frequencies. This is exactly what I was referring to. Normally you don't worry about it because these harmonics are being broadcast at such a low power compared to the primary that you wont see them. If you are near a high power broadcast transmitter though you may end up picking up on these. There can also be things such as your VFO mixing with A RF signal and producing a image. RF can be funny like that and these cheap SDR's don't have much hardware to combat that sort of thing.

Just to go over some things: When I click on the configure button I set my device to what shows up as "ezcap USB 2.0 DVB-T/DVB/FM dongle" this isn't the dongle i have but the chip set is the same so the driver works. This should be what yours says. Also I have mine at 1.8 MSPS. You can pay with this a little. I found that its a good starting point. For sampling select quadrature sampling. So under the tuning section I select Offset tuning and moved the adjustment point to 36.4db or in that range. The AGC and offset tuning is something that will need to be played with. If the gain is set to high you will get overloading and signals will get washed out and hard to see. If you set it low you will not see anything. Play around with it and watch how signals react on the waterfall. So once you have that set up you can close that window and go back to the main screen. If you are looking for Local fire dept, Police, weather station etc... you will want to set the radio to NFM. If you are looking at broadcast set to WFM. I found that the filter type doesn't matter much for this. I have mine at Blackman-Harris. For now the filter you will want to set the filter bandwidth to 12500. I have my filter order set and 10 and to be honest I don't know much about what that does but if you make it more you get less signal. For now I would uncheck your squelch just to hear the static. Mine is on and set at 66 because my noise floor is at -60 to -65db at this frequency. step size is 12.5khz and I have the correct IQ set. That should take care of the radio side of tuning in to FM frequencies. The last step would be to make sure under the Audio section that you have the output set to your computer soundcard output. I hope that going over some of these steps will help.

The RTL-SDR is crazy good for the price but there are some things about it that just aren't that good. I would suggest searching for calibrating a rtl-sdr. The weather channels are typically pretty good at being on frequency and if you know what it is transmitting at you offset your sdr to match that frequency. The other problem is that these things have poor filtering and shielding. You may be seeing two signals (internal of the sdr mixed with external signal maybe) and end up with a signal showing up on your screen that is out of place and in reality not at that frequency. This could explain a FM station down that low. Also if you are near the Broadcast transmitter it could also just be spurious transmissions from the radio station that you are picking up because you are so close.

If you have SDR# installed and the rtl-sdr plugged in you would want to select the rtl-sdr/usb from the drop down menu by the play button then press play. Once you press play you and adjust the VFO (Variable Frequency Oscillator) to the frequency you are looking for which in your case you are probably looking for activity in the 140mhz-170mhz and 430-480mhz. Just a guess on the frequency range because you stated two whole frequency bands which covers a lot. if you wanted a example of VHF you could set the vfo to read: 0.162.500.000 which will be 162.5MHZ which is in the VHF band and there is a good chance you will find a weather station near that frequency. I hope that helps.

Hey guys, I have been following along for a while and was happy to see some sdr action enter into the scene. I live in the north bay and have been watching some of the paging systems that are around here. Typically these are high power stations (some low band VHF, some High band VHF, some 400Mhz but mostly 800mhz) so getting a strong signal is easy with a stock rtl-sdr antenna. I am using PDW in windows (http://www.discriminator.nl/pdw/index-en.html). it may be worth while for members of this forum to check out. The amount of data that pours over the air from these is amazing. They send out data that isn't just local to the area but often is from other parts of the state. I have seen personal medical information get relayed from one medical staff to another during shift changes, status of equipment get sent out to techs (servers, HVAC, communication gear), Basketball game stats, Names of clients to be picked up by taxi services with contact numbers etc. I don't know if pagers are so old school they have been over looked or people just aren't interested in what they see but it seems to me that there is potential here. I would think that people smarter than me could write a program to sort this out by sender and start logging lots of info on a target. Check it out and see what you think. Keep the segments rolling, good stuff!