HN7000 and ranging

[dirkleearm]

Has anyone seen this problem?
HN7000S on Hor 1 1270, no tx errors while surfing the web including speed tests up and down, but massive ~90 % errors when trying to range/force range. The system takes a long time to finally range (~25 - 30 min). Trying to figure it out, I swapped odu, idu and bypassed house wiring. The only thing I did not have was a PS which is the low wattage one ( I think 45watts?). Tech support was of no help, they could only suggest from their list (things I had already done!). Also I had ran the odu on my system, force ranged etc with no problem. I suggested they (HN) were having an issue but was told they are not??? Not logical.
Also could someone explain what happens when "ranging", tech support could not.

 

[grohgreg]

Why did the customer have the old 45w power adapter? New HN7000S systems automatically come with 64w or larger, as should the modem-only upgrade packages. And as I'm sure you know, the 45w won't sufficiently power anything larger than a 1 watt transmitter either.

The adaptive inroute capability of the HN-series means the modem varies its L-band output level proportionate to SQF samplings. A drop in SQF typically signifies atmospheric attenuation (rain fade), so the modem increases the L-band output to the transmitter to compensate. To do this, the modem needs more DC from the power adapter.

When ranging, the modem increases L-band output until it gets an "I see you" signal from NOC equipment. Your 45w power adapter may be at max output, and still not be providing sufficient DC power to get a ranging signal of sufficient strength to the NOC.

Cable loss could also be contributing. So first thing I'd do is a loop resistivity test - IDU to ODU - on each cable path (FSB 0510-19-1A). Replace any suspect cables and test again. If/when they pass, replace the 45w power adapter with the standard HN7000S power brick - and try ranging again.

Ranging itself is the process of determining time and distance to satellite. Time and distance are critical to obtaining/maintaining/recovering synchronization with the network timing loop. Distance is simple Pythagorean theorum, calculated from where the modem has been told it's located (ZIP or Lat/Lon). Time however, has to be done with something like a PING. The modem sends the ranging carrier to the satellite, which relays it back down to the NOC - who sends it back to the customer. A total elapsed time is obtained. The NOC knows it's own time to/from satellite, so that's subtracted from the total. The remainder is the customer time to/from satellite. To give you an idea of how critical the ranging time is, the result is recorded in your modem to the 7th decimal point. My current time to satellite (and back) for example, is .2503698 seconds (or 250.3698ms).

//greg//

 

[dirkleearm]

Thanks for the reply. The time to/from sat being important because noc knows when to send more packets??
Also I put a lot of 7000s modems in with the 45 watt ps. I asked tech support if that could be the problem, but it wasn't on his list.............

 

[grohgreg]

The time to/from sat being important because noc knows when to send more packets??

That's part of it, but network timing sync is more encompassing than that. It's the fabric that holds the network together. One thread for each customer. Consider that one Ku-transponder serves over 12,000 subscribers. Each has a unique slot in the timing loop. Without sync with the loop, a customer can't even queue up for a timing slot to access the gateway server. Once granted access to/thru the gateway, THEN the NOC can "send more packets".

Not positive, but I believe a DW7000 is ok with a 45w power adapter - and that it's the HN7000S that requires it. All the same, you apparently have some HN7000s customers that are getting by with the 45. In that case, it's even more important to do the loop resistivity tests on this problem installation you describe.

For comparison purposes, I just put in a 2w pure Osiris system with a 110' cable run. I used Belden 1829BC and 3GHz fittings all the way. I connected the TX and RX cables together behind the modem, using a 3 GHz barrel connector. Out at the ODU, loop resisitance between center conductor measured 1.6 ohms, as did the shielding. Since Hughes spec for a 2w Osiris on up to 249' of 1829BC is 5 ohms per leg, so I didn't even bother shorting the individual cables. There are different specs for different lengths of different (approved) cables connecting the various ODUs - it's all spelled out in FSBs 060316-01b and 05019-01a

//greg//