Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

FSK high and low data rate transmission

Status
Not open for further replies.
W

Wirecomm

Newbie level 2
Joined
Feb 11, 2013
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,296
I have a device which works transmits and receives FSK modulated signals .
It operates at two rates 9.6 and 40kbps data rate. When there not much loss in the link it receives data at 40kbps and when loss is more it receives packet at 9.6kbps with same modulation technic in both cases. How does this happen. How is the receiver able to decide low data rate packets?
 

without actually knowing which device you are referring to, i would guess that your Tx and Rx boxes have an internal control channel between them as well, where the Rx unit is able to send info back to the Tx unit.

Now when the Rx receives data at 40Kbps which is erroneous - decided based on parity/ CRC/ other method - it simply sends a control message back to the Tx to slow down.
 

kripacharya said:
without actually knowing which device you are referring to, i would guess that your Tx and Rx boxes have an internal control channel between them as well, where the Rx unit is able to send info back to the Tx unit.

Now when the Rx receives data at 40Kbps which is erroneous - decided based on parity/ CRC/ other method - it simply sends a control message back to the Tx to slow down.
Click to expand...

Wirecomm: yes there is feedback mechanism like Ack and naks which is transmitted to sender .
Allowing transmitter to reduce the rate . But again I have a basic question of how is that the receiver is able to decode low rate bits with same FSK modulation?. Is it because receiver has more time to accumulate energy from low bit rate traffic?.
Please clarify.
Thanks.
 

Maybe because of clock (timing) recovery technique like e.g. early-late gate on packet preamble?
 

Wirecomm said:
able to decode low rate bits with same FSK modulation?. Is it because receiver has more time to accumulate energy from low bit rate traffic?.
Please clarify.
Thanks.
Click to expand...

something like that. assuming the noise floor is the same, then for a lower bitrate the Eb/No ratio becomes higher and a receiver is able to recover more easily.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top