Hello list!
I've been digging a bit into the osmo-bts project to explore the GSM stack, and only ever see config information assuming you have a full-duplex TRX radio. I have a HackRF One I'd like to use for TX and an RTL-SDR I'd like to use for RX (both operating on the 900MHz GSM band), but cannot seem to find any configuration information for setting this up - even though I've seen some mentions in passing to osmo-bts-trx supporing RTL-SDR devices. I really don't have the budget to drop a few hundred more on a USRP device just to tinker with GSM and was hoping I could get away with two dedicated radios.
Can anyone tell me 1. if this kind of setup is even supported and 2. if so, point me to reference material that might help me make the connection?
Thanks in advance!
-Rob
- if this kind of setup is even supported
It's not.
Hi Sylvain,
This answer made me curious. Is it because it is not implemented yet or because you need an exact (same) clock for the Rx and Tx part. Or is it because of something else.
Thanks in advance for the answer.
Kind regards Philipp
Hi,
This answer made me curious. Is it because it is not implemented yet or because you need an exact (same) clock for the Rx and Tx part. Or is it because of something else.
You need the exact same clock (or at the very least phase locked ones, you could have different sample rates if they are locked you can always resample in software). Then you also need to know absolute time sync (i.e. which sample of TX matches exactly which sample on the RX side).
Theses requirements, while not impossible to achieve would impose some hardware modifications to whatever cheap SDR you try to use (like hackrf for TX and RTL-SDR for RX), making it hard to reproduce. It would also required _a_lot_ of work on the software side to deal with all the peculiarities of such a system. And finally there are cheap-ish full duplex SDR.
So simply put, there is too high a cost and too low a reward to bother. I mean, if someone has a spare 100kEUR in their couch cushion to finance the dev, I'm sure I can get that implemented.
Cheers,
Sylvain
Thanks for the quick reply. If you don't mind me asking, what would you recommend as the least expensive option that you know is fully supported by the Osmocomm stack?
-Rob
On 12/7/2020 6:13 PM, Sylvain Munaut wrote:
- if this kind of setup is even supported
It's not.
Cheers,
Sylvain
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Philipp Psurek -
Robert Bates (Octobang) -
Sylvain Munaut