SatSig topic:

NO RX

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Sep 17^th, 2009 at 3:33pm

Hello everyone
I am at the following problem:
After the programming of two terminals 5150, at a hub in a network, I see that these two terminals does not unlock the downsream. (NO RX)
Although
- With a spectrum analyzer can be seen clearly the downstream on the RX out port of the remote
- the RX Ifl10 is very stable + Rx iflDC is 22V
- I used several LNB deferential stability.
The problem still persists there a solution?

Sep 17^th, 2009 at 10:27pm

1. Does the IDS on your remote match that on your Hub? Please double check it.
2. What is your downstream center freq (RF)?
3. What is the LO of your LNB?
4. What is the downstream center freq specified in your options file (in Lband?)
5. Is the Green LED lit on the back of your modem indicating the presence of DC? Cant you confirm that DC presence with a multimeter?

Confirm the downstream center freq in your options file is accurate by typing rx freq in telnet. Is the Lband freq the freq you were using on specan via rx IF port of the iDirect?

Sep 22^nd, 2009 at 9:55am

dear Mike

when I put another remote in the same network and with the same RF component it works very well.
The version of the remote is the same as the hub.
"Generated_by NMS version = $ Name: $ netmodem-8_3_1_0"
The LNB power LED is green and outDC is 18.87V (LNB is powred because I can see the signal on the spectrum analyzer on the port RX OUT of modem).

RF Dn CF = 14188.55 MHz – LNB LO = 10 Ghz - transponder trans = 3050

[MODEM_PARAMETERS]
rx_freq = 1138549999
rx_acqrange = 1800000
rx_bitrate = 2379638
rx_mode = 2
rx_modtype = 1
rx_fecrate = 15
rx_scram = 1
rx_diff = 0
rx_specinv = 0
tx_freq = 1000000000
tx_bitrate = 1460083
tx_mode = 0
tx_modtype = 1
tx_clksource = 0
tx_fecrate = 5
tx_scram = 1
tx_diff = 0
tx_specinv = 0
tx_power_in_dbm = -19.000000
rx_fsd = 124027
tx_spreading_factor = 1
rx_spreading_factor = 1
tx_spread_enable = 0
rx_spread_enable = 0
is_demod2_active = 0
rx_symrate = 1499999.576485
tx_symrate = 1105861

[ACQUISITION_PARAMETERS]
fsd = 124498
thanks for your help

Sep 22^nd, 2009 at 12:43pm

14188.55 is your Hub RF Up (vice your RF Dn and you mentioned above)

That said,

14188.55-3050 (craft trans) = 11138.55 RF Down

11138.55 - 10000 (LNB LO of 10.0 GHz) = 1138.55 (Rx IF at the iDirect)

...which is what you are showing in your opt. However, need you to telnet to that iDirect unit and actually run an rx freq command on it to confirm that it is IN FACT 1138.55 (as the operational rx freq, as specified in the options file). Just cross checking.

If you can see that lband freq on the IF RX Port. Clearly something is amiss in falcon. This is happening on two systems?

M

Sep 22^nd, 2009 at 1:40pm

yes i have this problem in tow remotes
this result of telnet commandes:

[RMT:3457] admin@telnet:::ffff:127.0.0.1;1024
> rx snr
Rx SNR: -100.000000

[RMT:3457] admin@telnet:::ffff:127.0.0.1;1024
> rx freq
Rx Frequency = 1138.5500 MHz
and in the RX out port i see clairely the downstream.
NB: this Downstream is used by 30 remotes with no Problem.

Sep 23^rd, 2009 at 1:20am

Are you certain that you have an accurate stability identified in the LNB RFT of that remote? Are the 30 remotes using the same setting for stability?

It is clear that you have the right LO and you are getting the right translation (L-band), but something is preventing that SNR from getting to the modem.

When you rolled in the "other modem" (the one that worked, as you mentioned), were you using:

1. the same rx/downlink IF cabling?
2. LNB the same?

Sep 25^th, 2009 at 11:26am

dear mike
I tested The 30 terminals with the same RFT before deploying them on their actual locations.
In addition . this RFT is used as witns site, All going well except the two 5150.

Sep 25^th, 2009 at 11:53am

Is there any chance that your downstream carrier specs changed (any) between now and then? Even the slightest change in Modulation or codings could yield what you describe. Has the symbol rate on the forward changed (at all) since you loaded the options files?

You are getting the proper translation, and the Lband freq specified in your opt appears to be correct - based on the RF down center freq you provided. If you have used the RFT on other system, that also points to being good and the stability setting is correct.

Faulty demod possibly?

Sep 25^th, 2009 at 12:38pm

What type/model number of LNB is in use ?

If the LNB frequency stability is poor - and some DRO LNBs are rather bad, then the actual frequency may be outside the modem capture range. Try widening out the acquision range.

If you have an accurate spectrum analyser, what is the actual measured L band receive carrier frequency ?

rx_freq = 1138549999
rx_acqrange = 1800000
rx_bitrate = 2379638

If this particular LNB is 2 MHz off frequency then the modem won't find and lock to the carrier.

Question to Mike: Is the rx_acqrange = 1800000 the total acquisition sweep range or does it mean +/- 1800000 either side of nominal ?.

Best regards, Eric.

Sep 26^th, 2009 at 2:12pm

Eric, I am pretty sure that it is the total range, but let be run it to ground to be sure.

To the thread starter: Was the same LNB used on the "good" modems?

Oct 5^th, 2009 at 9:11am

eric and mike
thanks for replay
I'm sure it's not a LNB's problem because I used multiple LNB, and the result is the same (with his good remotes works fine but with the terminals in question its not work).

Oct 5^th, 2009 at 11:03am

Hello,
I suggest to clone other remote from the network (witch work fine) and after that modify the serial number (must be different) and the other RF equipment, IP default, GEO location etc witch are different.
I say that because if you see at the Rx out of the terminal, the downstream carrier from the Hub at the normal level and at the corect center frequecncy it is possible like option file to be different (type of modulation, fec or something else).
Also, check the remote package for the terminal. Must be the same version with OS iDirect used. Can you acces the remote with the iSite ?

Best regards,
Adrian

Oct 27^th, 2009 at 12:05pm

when i clone an other remote with the same parameteres it work fine
Quote:

Hello,
I suggest to clone other remote from the network (witch work fine) and after that modify the serial number (must be different) and the other RF equipment, IP default, GEO location etc witch are different.
I say that because if you see at the Rx out of the terminal, the downstream carrier from the Hub at the normal level and at the corect center frequecncy it is possible like option file to be different (type of modulation, fec or something else).
Also, check the remote package for the terminal. Must be the same version with OS iDirect used. Can you acces the remote with the iSite ?

Best regards,
Adrian