Most quality industrial DC power supplies are adjustable and designed for wide range of temps. Just saying On Jan 21, 2016 8:30 AM, "Steve D" <bigd...@gmail.com> wrote:
> Just throwing this out there, but don't the epmp's have a small heater in > them that could be turning on when it's cold, drawing additional power? I > recall it was supposed to pre-heat components to avoid freezeup on first > boot but I can't recall if that's the only time they run or not. > > -Steve D > > On Thu, Jan 21, 2016 at 1:44 AM, Forrest Christian (List Account) < > li...@packetflux.com> wrote: > >> I do want to clarify one item: >> >> This is not necessarily related to the cambium DRAM issue. I don't want >> to claim that problem, since this isn't the same thing. This is more of >> an issue where you have ePMP's which seem to start having power-related >> issues. If moving to a 30V brick makes your problem go away, then the >> issue I describe below probably is your issue. If moving to a higher >> voltage doesn't fix the issue then this probably doesn't relate to your >> issue. Regardless, it is my intent to recommend that my customers move to >> 48V as soon as I confirm that this seems to fix at least a decent number of >> the problems without causing others. >> >> Unfortunately this might be a case of the cold weather aggravating two >> separate issues (or for that matter, the cold weather causing increased >> current consumption in the ePMP, which then requires a higher voltage to >> operate correctly). >> >> -forrest >> >> On Thu, Jan 21, 2016 at 12:43 AM, Forrest Christian (List Account) < >> li...@packetflux.com> wrote: >> >>> 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> >>> >>> >> >> >> -- >> *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> >> >> >
