A bit of an update from the PacketFlux side. Late this afternoon I received a ticket from Tyson in relation to these issues. In particular, sync from a PacketFlux SyncInjector dropping off on an ePMP when it's cold. I have spent a bit of time this evening investigating this issue. The following is a summary of what I found. It's a bit long-winded so that those experiencing the problems can understand my current working theory and help me figure out if this is the case.
WARNING: The following is based on a limited amount of testing with a single ePMP with no traffic and no clients and on a bench. This is likely the best case scenario. The field is only going to be worse. The setup is as follows: ePMP 1000 GPS AP, with no GPS hockey puck attached, connected to a Gigabit Syncinjector (Rev H and Rev I - I have a special one with a port of each 'type' ;-) ). I am powering the injector with a variable power supply so I can vary the voltages in. The AP is connected to the Injector with ~100m of CAT5 cable. The Antenna connectors have terminators on them, the AP is in transmit mode, but isn't passing any traffic since there are no clients. When feeding the injector with 24V, I get about 23V at the AP. This is pretty consistent with what I would expect in this situation. The AP seems to work fine, at least on the bench and without doing any real work. However, as the voltage drops, things start to get weird: At around 22V in, (21V at the AP), Sync becomes flaky. This is consistent on both H and I version ports on the injector. Sometimes it works, sometimes it doesn't. Note that 22V is the bottom of the rated voltage inputs for the ePMP. At around 20.5V in (19.5V at the AP), the radio just turns off. It won't turn back on until around 22V. Now here's where some total speculation comes to play. On the bench, this unit is drawing around 3W. Let's assume that under load, and when temperatures are cold, this unit draws closer to 6W. This would double the current, and quadruple the voltage drop. Now, assume 24V in, this puts you at around 20V in at the AP, which is about the turnoff point. Remember this is on 100m of wire, and a total speculation about a the power draw of a cold, under load AP. But the point is valid, regardless of the cause - if the circuit resistance when combined with the power load causes a low enough voltage at the AP, weird things will happen. And since weird things seem to start to happen around 22V, there just isn't much headroom at 24V. This explains why things work well at 30V. For those who are having this problem I'd recommend trying increasing the voltage into the SyncInjector. The Revision H injectors can safely handle up to around 56V or so. Assuming all of the radios on an injector are either ePMP or the newer 450i's, using 56V into a SyncInjector is perfectly acceptable and the ePMP's are rated up to 56V as well. So the summary: Try a 48VDC voltage source instead of 24V and see what happens. -forrest On Wed, Jan 20, 2016 at 11:00 AM, Tyson Burris @ Internet Communications Inc <t...@franklinisp.net> wrote: > Hello Cambium, > > > > At the MidWest-IX launch party last night, several of us Indiana WISPs > compared notes on the ‘cold weather’ problems we are seeing with ePMPs. It > was very interesting to learn we are experience identical problems across > the spectrum. > > We all understand this is a DRAM issue with certain units you have > identified. We also understand the firmware RC that has been made > available to fix this short term. > > The bottom line is we are very frustrated and grow tired of dealing with > it. > > > > Our concern is simple. If your software fix ‘degrades’ the performance of > the product or triggers other issues, as it has been suggested, we would > prefer a full recall and replacement program immediately. > > > > If the suggestion that the fix will degrade the product performance is > inaccurate and not cause other issues, I would like for this to be made > public. > > > > Thank you, > > > > *Tyson Burris, President* > *Internet Communications Inc.* > *739 Commerce Dr.* > *Franklin, IN 46131* > > *317-738-0320 <317-738-0320> Daytime #* > *317-412-1540 <317-412-1540> Cell/Direct #* > *Online: **www.surfici.net* <http://www.surfici.net> > > > > [image: ICI] > > *What can ICI do for you?* > > > *Broadband Wireless - PtP/PtMP Solutions - WiMax - Mesh Wifi/Hotzones - IP > Security - Fiber - Tower - Infrastructure.* > > *CONFIDENTIALITY NOTICE: This e-mail is intended for the* > *addressee shown. It contains information that is* > *confidential and protected from disclosure. Any review,* > *dissemination or use of this transmission or its contents by* > *unauthorized organizations or individuals is strictly* > *prohibited.* > > > -- *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 forre...@imach.com | http://www.packetflux.com <http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux> <http://twitter.com/@packetflux>
