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From: | neil shelley |
Subject: | [Discuss-gnuradio] Using two USRPs - how to synchronise a receiver (scan a range of frequencies) looking for a transmitter which is transmitting on a specific frequency |
Date: | Thu, 20 Jul 2017 19:04:57 +0000 |
Hi all,
We are currently doing a project, which aims to look for white space over a chosen frequency range, automatically select the best channel (considering a 1 Mhz span with 5 channels, each of 200kHz). The transmitter would tune to the centre frequency of this best channel, and the receiver should be able to detect this transmission from the 1Mhz range, and perform a handshake with the transmitter so the transmitter knows the receiver has identified the chosen frequency. The transmitter should then transmit the information (i.e a text file).
For the sending a text file part, we have been able to do this using QPSK and GMSK with partial success (however the text file is missing information at the end), the main part we have not been able to resolve is how the USRP receiver could detect the chosen frequency, and then let the transmitter know it has identified this.
Can anyone suggest some ways in which this can be done, I have broken it into a few stages: 1) How to get the transmitter to continuously transmit at the specific frequency (i.e either 710.1, 710.3, 710.5, 710.7, 710.9 (Mhz) - what should be transmitted, e.g. a type of continuous code that could be identified by the receiver?
2) What is a good way to get the receiver to scan the 5 frequencies, and at each frequency, how could it identify that this is a transmission from the correct device, i.e using an access code, or a tag of some sort?, if it does not identify this as the required
transmission then it will move on to the next frequency.
3) Once the receiver has detected the correct frequency, how can it inform the transmitter that it has identified this frequency is to be used and tell it to start transmitting the real information (the text file).
I know this is probably a lot to ask, but any help on any part of it, or some ideas that we can start to look at would be appreciated.
Thanks,
Neil. From: Discuss-gnuradio <discuss-gnuradio-bounces+address@hidden> on behalf of address@hidden <address@hidden>
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