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protocol_details [2015/12/23 16:07]
russ Add an SDR image
protocol_details [2016/08/31 16:31] (current)
russ
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 ====== UKHASnet Layer 1 & 2 protocol details ====== ====== UKHASnet Layer 1 & 2 protocol details ======
 {{ :​ukhasnet-packet.png?​200|}} {{ :​ukhasnet-packet.png?​200|}}
-Layer 1: 
- 
-  * 869.5MHz centre frequency 
-  * 24kHz total shift, deviating 12kHz above centre for '​1'​ 
-  * 2000 baud 
-  * 2FSK 
-  * all bytes transmitted most significant bit first 
- 
-Layer 2 frame format: 
- 
-  * 3 byte preamble, 2 byte sync sequence, Length, Data Bytes, CCITT CRC-16 checksum 
-  * Preamble: 0xAA, 0xAA, 0xAA 
-  * Synchronisation word: 0x2D then 0xAA, transmitted MSb first 
-  * No address byte 
-  * Single byte length (0 - 255) - currently limited to 1 - 64 by application layer. 
-  * No Manchester coding or Data Whitening - so the application must ensure sufficient bit transitions in the data to retain synchronisation 
-  * Checksum is polynominal 0x1021 and starting bits 0x1D0F, XORd with 0xFFFF at the end, calculated over the length and data fields, transmitted MSB and MSb first. 
- 
-example: 
-0xAA, 0xAA, 0xAA, 0x2D, 0xAA, Length, Data, Data, Data, ...., CRC16, ​ CRC16 
  
-Frame contains "​Length"​ bytes of "​Data"​+The protocol description can now be [[https://​github.com/​UKHASnet/​protocol/​blob/​master/​protocol.md|found on GitHub]].
  
 The sound of a UKHASnet packet followed by it being forwarded - on a wideband FM radio The sound of a UKHASnet packet followed by it being forwarded - on a wideband FM radio
  
 {{::​ukhasnetbursts.wav|}} {{::​ukhasnetbursts.wav|}}
protocol_details.txt ยท Last modified: 2016/08/31 16:31 by russ