ARLA/CLUSTER: ID-1 sensitivity in D-Star.

[João Gonçalves Costa]

1a. ID-1 sensitivity

Hi Guy!
I looking some information about the real sensitivity of ID-1 in DD mode. This is because in DV mode with a signal around S1-S2 we have a good QSO with a correct exchange of low speed data, but in DD mode is need more than S8 signal for estabilish a connection.
Any idea?

73 de Antonio IW2OAZ
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1b. Re: ID-1 sensitivity
    Posted by: "Evans Mitchell KD4EFM / AFA4TH FL / WQFK-
    Date: Sat Feb 14, 2009 12:40 pm ((PST))

Look at it this way....

this is a straw, this straw carries DV and Low Speed Data 2.5KHz narrow band

|        |
| 2.5Khz | 
|  DV    |
|        |


This the straw that carries 128Kbps Digital Data 130KHz WIDE BAND

|           128Khz            |
|           DATA              |
|                             |
|                             |
|-----------------------------|

This is poor designing, but, if you have studied the waveform for 802.11 b/g, you will know that in 802.11 g uses more bandwidth space then b (OFDM vs CCK)

You need more power for more bandwidth, therefore you need more signal on 23cm for the same reasons, larger bandwidth needs more signal input / output.
Problem is, no one makes an bi-directional amplifier that can switch fast enough for D-Star Data. SO with that, you have to factor every "SPECK" of gain you can get, and have absolute Line Of Sight.

Right now, our system can do 35 air miles Near-LOS with our PORT A DD at 360' and the far end user at 50'.
He can establish communications with the DD box.

WE DO KNOW that beyond 40 miles, it does fail with only a 9Dbi gain at 60 feet, BUT they can decode the DD.
They also have a 24Dbi parabolic at 40 feet and hit the DD rock solid from 40 miles out.

So again, GAIN IS EVERYTHING. Just because you can get in on voice, does not mean you have to POW to make it on DD.

Evans
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1d. Re: ID-1 sensitivity
    Posted by: "Adrian" 
    Date: Sat Feb 14, 2009 5:39 pm ((PST))


There are specifications in the manual

FM    Less than 0.18uV
DV    Less than 0.35uV
DD    Less than 1.58uV

The DD mode will need a stronger signal as the bandwidth is higher as stated in the previous replies.

Adrian.
GM1FML

Fonte: dstar_digital  yahoogroups.com