Hi,
I am working on a small project where there is a need to receive a FM signal and then apply some audio processing functions in the GNU radio environment. I am sure that the bladeRF is capable of the same.
I have got the bladeRF setup running with the gnu radio as well. I have two questions in this regard:
1) Do i need a tranverter board (as i understand i may not need it) to receive the FM signal ?
2) What are some suggested antennas that can be used for this purpose. Also what is the impedance that I should be matching for connecting the antenna to the bladeRF SMA connectors. From what i have read looks like 50 ohm is recommended but wanted to confirm.
appreciate response on this !
Thanks,
Ram
Antenna suggestions for working with FM signals
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ram_tenet
- Posts: 1
- Joined: Wed Feb 04, 2015 12:16 am
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jynik
- Posts: 455
- Joined: Thu Jun 06, 2013 8:15 pm
Re: Antenna suggestions for working with FM signals
Hi there,
1) The transverter is certainly the quickest and easiest way to tune lower than the 300 MHz limit on the LMS6002D, with a few on-board filterbanks for popular HAM bands.
As SM5BSZ showed, you can also use the ADC directly, without requiring the XB200 transverter. However, as noted by Leif and issue #301 there's some work needed to investigate improve that direct sampling quality.
The XB-200 transverter has a "custom filterbank" path that you can select in software. In this path, you can insert an apporpriate filter for the desired FM bands. However, when receiving from strong FM stations, you'll generally be able to get away with SMA cable across this path (thereby using no filter) and receive FM just fine. With weaker signals or if you're encountering noise/interference, putting an appropriate filter in there would certainly be a good idea...
2) You are correct about needing a 50 ohm load, with an SMA male connection.
I don't have any particular make/model that I'd recommend; you can usually find some good deals on Ebay, using the above items for search queries (and of course the band/frequencies for the antenna).
For what it's worth, I can pick up local FM radio stations quite nicely with an SMA cable across the XB200's custom filterbank path and this antenna from a Yaesu VX-7R, which is not really intended for FM radio frequencies, but suffices to a certain level of "good enough."
On a final note - you said "small project to receive FM." While I'd certainly be happy if you decided on a bladeRF, I just wanted to ask if you've looked at cheaper options of using RTL-SDR or something, given that you indicated your project to be of limited scope.
Hope that helps,
Jon
1) The transverter is certainly the quickest and easiest way to tune lower than the 300 MHz limit on the LMS6002D, with a few on-board filterbanks for popular HAM bands.
As SM5BSZ showed, you can also use the ADC directly, without requiring the XB200 transverter. However, as noted by Leif and issue #301 there's some work needed to investigate improve that direct sampling quality.
The XB-200 transverter has a "custom filterbank" path that you can select in software. In this path, you can insert an apporpriate filter for the desired FM bands. However, when receiving from strong FM stations, you'll generally be able to get away with SMA cable across this path (thereby using no filter) and receive FM just fine. With weaker signals or if you're encountering noise/interference, putting an appropriate filter in there would certainly be a good idea...
2) You are correct about needing a 50 ohm load, with an SMA male connection.
I don't have any particular make/model that I'd recommend; you can usually find some good deals on Ebay, using the above items for search queries (and of course the band/frequencies for the antenna).
For what it's worth, I can pick up local FM radio stations quite nicely with an SMA cable across the XB200's custom filterbank path and this antenna from a Yaesu VX-7R, which is not really intended for FM radio frequencies, but suffices to a certain level of "good enough."
On a final note - you said "small project to receive FM." While I'd certainly be happy if you decided on a bladeRF, I just wanted to ask if you've looked at cheaper options of using RTL-SDR or something, given that you indicated your project to be of limited scope.
Hope that helps,
Jon