SatSig topic:

LinkStar modem problem at FOB

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May 27^th, 2008 at 4:32am

a bentley walker system with a ViaSat LinkStar S2 modem, and on an existing account. We moved the dish from one side of the FOB to another and now it preforms its power on test. Then it keeps the ODU and Power lights on. So we failing to have a meter used a compass and shot an azimuth off a nearby dish that is currently working. So we are pointed within a degree or less of the other dish. Now every five minutes or so the SAT light and the ALM lights come on and stay on from 1 minute to 30 minutes then they go off again. Please any help is greatly welcomed.

May 27^th, 2008 at 11:38am

Also anyone familier with setup on FOB Methar Lam in Afghanistan give me a heading for my compass please.

May 27^th, 2008 at 5:33pm

I've recently added an azimuth angle line to the maps that are drawn by this page https://www.satsig.net/maps/satellite-dish-pointing-iraq.htm
I know the map starts in Iraq but you can drag it sideways to Afghanistan.

I do wonder if you have peaked up the pointing. You need to read the QPSK bit error rate many times and adjust the az-el nuts in fractions of a turn. It will take at least 30 minutes work to peak up once you have found the satellite. More than 20 BER measurements may be needed as you progressively peak up. Ideally you want the PC screen at the antenna - otherwise two very patient and persistent people, one at each end. Get the BER to the minimum. e.g. 0.00003 Four zeros after the decimal point is good.

The command rep tcmp may cause the BER display every 5 seconds - but I don't know how to stop this.

Best regards, Eric.

May 28^th, 2008 at 4:40am

Eric, Where can I lay my hands on the software to talk to the Sat modem? I have no meter and no software to read what the modem is telling me. Right now I have adjusted it so that the ALM and SAT lights are blinking about every 60 seconds but otherwise on all the time.

May 28^th, 2008 at 10:55am

Sir,

The modem can be accessed using telnet, no software is required.

It appears in this scenario,that the problem is purely down to pointing, failing that there may be an issue with the installation itself, in terms of either antenna assembly or the way the modem is connected to the odu. The 5 minute change in status is a reboot, the modem will restart if it does not lock onto the satellite.

Please feel free to contact me directly for support: james@bentleywalker.com

If you need assistance with connecting to the modem, again please do not hesitate to contact BW direct.

Contact numbers on our website www.bentleywalker.com

Eric,

To stop rep tcmp you can enter another command and it will stop the repeat process. Thanks for your assistance.

James

May 28^th, 2008 at 4:57pm

Connect a PC direct to the Linkstar modem, using cross over cable.

Open a command prompt window and type
ping xxx.xxx.xxx.xxx where xxx.xxx.xxx.xxx is the gateway IP address of your modem. The purpose of this test is to verify basic IP communications between your PC and the LinkStar modem.

If ping works Ok then try telnet xxxx.xxx.xxx.xxx

If ping and telnet do not work you have wrong gateway, subnet mask or PC IP address.

If your LinkStar has been comissioned and worked before, see how previous PC or router was set up. Maybe the documentation says what to use.

If the LinkStar is new and has not been commissioned then...

The subnet mask during the initial set up process is 255.255.255.0

It will change to something like 255.255.255.248 after it is commissioned and has its new operational gateway IP address.

During initial set up the modem gateway IP address is like 10.0.xxx.xxx or 10.1.xxx.xxx or 10.2.xxx.xxx or 10.2.xxx.xxx where last (three) two numbers are the last (three) two terms in the MAC address. e.g. 3B = 59 and 7F = 127 Use the PC calculator in scientific mode to convert (Hex to Decimal).

The oldest modems start with 10.0, more recent with 10.1, 10.2 or 10.3

Set your PC network interface so the gateway is the IP address of the modem. Set the subnet mask to 255.255.255.0 Set the IP address of your PC to something different in the last digit position e.g. 10.x.59.128

See here for an old linkstar installation guide 700kbytes pdf

In the above example you would go to the comand prompt (black window) and type telnet 10.1.58.127

Hope this all helps. I don't have a LinkStar here so can't reproduce the exact situation. Seek help from BW if there are still problems - i.e. my advice is wrong.

At the telnet command window type
tcmp to see what is the raw QPSKBER
0.4123456 is very bad
0.003 is getting better
0.00001 is excellent
type rep tcmp to see the measurement every 5 seconds, while you adjust the nuts.

type pconf to see the configuration. If yours was a new service or new satellite then BW will have provided you with a configuration string to type in. This is a single line of text that sets the frequency, symbol rate etc for the downlink receive carrier. If you are simply moving the antenna from one place where it was in use recently, to another nearby place, the old config will have been retained and will not need reentering.

With just the LNB cable connected I would expect to see the receive SAT LED start slow flashing green as you get near the satellte in azimuth and go out again after you have gone past it. Leave in the middle and peak up in elevation. Peak up to minimise the QPSKBER. Power off and join up the Transmit BUC cable. The SAT LED should go slow flash, fast flash and eventually solid green.

Never ever get the Receive LNB and Transmit BUC cables crossed over.

Best regards, Eric.

May 29^th, 2008 at 3:24am

I am working on testing all the advice given me here. I and my fellow soldiers are grateful for all the advice so far. I have converted the MAC address and will be getting with the person I bought it from to see if he changed the default IP address. I had previously discovered that it was set to 255.255.255.255 for the subnet mask through serindipity. Same way I got the dish tuned to the proximity of being correct that it is. The Last time I worked with Sat Com I was working for BP Exploration and that was already setup I just had to take care of the network;) LOL

May 29^th, 2008 at 7:31pm

useing a carpenters speed square, a two foot level, a piece of string with a weaight on it, and a protractor we have set every angle on our dish to match our neighbors who is same altitude, and everything. (their dish works) and nothing howeve ronce I telneted into the modem thos was the only thing I found odd other then the lack of data present.

** TDM Statistics Menu **

00. Return to main menu
01. DVB-S Rx (may disturb rx!)
02. NCR Synchronization Status
03. IP Packets From DVB-S

Enter item number [0-3]: 1
Command: tcmp
Standard       DVB-S1 Synced 0
RSCorrectedErrCount       0 RSUncorrectedErrCount    0
UncodedBER -1.000000 I2CErrorCount       0
LostSyncCount       0 TimeSynced    0
TimeUnSynced 0 MaxTimeSynced       0
CarrDeviation       0 NCODeviation    -7610
RSVit !LOCKED CarrierPhase !LOCKED
frequency    0 CodeRate    N/A
Rs    0 Fs    99
RxPower       0 EbNo 0.3599999

BER -1.000000
Buffer Level 0

May 30^th, 2008 at 2:13pm

Well done getting a PC to communicate with the modem.

The LNB (small white device on filter side arm) must be connected to the receive satellite IN socket on the modem. Physically follow the cable to check. The centre pin of the F connector should stick out 1.5mm, it should go smoothly into the socket hole and not push back the cable. The outer screen/braid of the coax must make good contact also. If the centre pin appears corroded or the braid screen looks like it is covered in white powder then moisture may have affected some distance into the cable. Cut back the cover braid and remake the connector.

The configuration (downlink receive frequency, symbol rate etc) must match the wanted satellite. Read out the pconf to check the current configuration. The configuration is set by typing in a configuration string - a single long text line of cryptic letters and numbers.

The dish must be pointed. Having set the polarisation adjust the elevation accurately. Then swing the dish boldly across the approximate azimuth till the RX LED starts flashing green. Peak up using tcmp and minimising the BER. If you don't find the satellite on the first swing try changing the elevation in 1 deg steps.

Best regards, Eric.

Jul 10^th, 2008 at 2:49pm

As it turned out I had a bad modem. I recieved my new modem, and now the system is good. However now I am running into a networking problem. I have 13 IP addresses available, and 29 users. Easily solved I thought. I ran a Linksys WAP54G 3.1 Access point and started linking people up however it still refuses to see them through to the internet if their IP address doesn't fall into the range given to me by Bentley Walker. Is their anything I can do that I am overlooking?

Jul 22^nd, 2008 at 12:25pm

If the number of PCs in your LAN is limited by the IP address range provided by the satellite modem it would seem that your Linksys WAP54 is configured as a hub rather than as a router. It simply distributes the 13 IP addresses you have been given as though it were a passive strip of 13 ethernet sockets. The satellite modem cable is on the same LAN as the wireless PCs.

If you operate your Linksys WAP54 in router mode you will have two networks.

The 'WAN' network will comprise the satellite modem port gateway IP address and the WAP54 Internet socket IP address. This network will only exploit 4 of 16 IP addresses: Network name, Gateway IP, WAP54 IP + 12 unused IPs, and Broadcast IP address. Subnet mask 255.255.255.240

The 'LAN' network will be your private wireless LAN and you need to invent any number of private IP addresses for all your PCs. e.g. For 29 useable PC IP addresses, LAN network name=192.168.0.0 gateway=192.168.0.1 Useable=192.168.0.2-30 Broadcast IP address=192.168.0.31 Subnet mask=255.255.255.224 Total IP addresses=32

This Linksys document may help: https://www.shooter.co.nz/Linksys_WAP54G_setup_procedures.pdf

Use this for subnet mask calculation: https://www.subnet-calculator.com/

Best regards, Eric.