DSSS or FHSS for short range radio link?

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mr_ghz

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Hi all

I have a short range radio link (<20 meters) which should be able to transmit small data pakets periodically. Because one station is moving I have big problems with fading. So I'm looking for a solution and found it in broadband transmission.
Now I'm at the point to decide between DSSS and FHSS. What do you mean / what would you prefere and why?

Thanks in advance
 

Re: DSSS vs. FHSS

What is the modulation scheme you are using? FSK or PSK?
 

Re: DSSS vs. FHSS

I think that it would be simpler to use just one frequency and have lots of error control code so you know if the data is corrupted. Then ask for a repeat if there are errors or if you want to save the cost of two way transmissions, repeat the transmission several times. Use FSK which is less sensitive to multipath.
 

if you do not expect a lot of interference from other sources it would be much easier to use direct sequence
 

Re: DSSS vs. FHSS

If you can implement Antenna Diversity in your system it will help a lot for fading. The same as the one used in some WLAN transceivers. But if your operating frequency is low the distance between antennas will be too high and the approach is useless.

regards
 

Using DSSS more easier than FHSS
 

Re: DSSS vs. FHSS

Thanks for your replies.
I plan to use a BPSK modulation on 2.4GHz. In an earlier project we have already used a narrow-band ASK modulation. We had a lot of trouble because of fadings (receiver is moving!). We had long times with no reception signal, so error correction is no solution.
Our idea was to increase the bandwidth (>50MHz) to not have this problems. It seems to me, that synchronisation is simpler in DSSS than FHSS (I also need broadband synchronisation in a short time...).
Are these ideas correct? Why does such a system not exist?

Bye
 

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