That's exactly the problem that the RevI injectors will fix. The reason it went away with a higher voltage is that the bottom of the dip that I showed in one of the traces above at the start shifts upward with voltage. So at 52 volts it doesn't dip as close to zero. As long as that dip isn't below about 30 volts, the 450i is happy - otherwise it detects it as a stray sync pulse and refuses to switch to that as a sync source. The RevI0 hardware should eliminate that dip altogether. With a longer cable, the dip is not only more severe, but there's also some additional voltage drop to contend with.
-forrest On Tue, Nov 10, 2015 at 10:12 AM, Matt <[email protected]> wrote: > FYI. Maybe unrelated but I had an issue with sync on a 450i. > > Mikrotik CRS --> Gigabit SyncInjector --> GIGE-APC-HV -- 260 foot shielded > cat-5 --> 450i. > > Would loose sync briefly dozen times a day or so. Increased voltage from > 48 to 52 volts. Issue went away, so far. No sync loss in bit over week > anyway. > > Identical setup with 210 foot of cable works fine with 48 volts. > > These are only two I have deployed but more on way. > > > > On Mon, Nov 9, 2015 at 4:21 PM, Forrest Christian (List Account) < > [email protected]> wrote: > >> We have recently become aware of a potential issue when using a >> SyncInjector with a PMP450i. The short version of this issue is that with >> certain cable runs (mostly longer ones), a PMP450i will refuse to accept >> the sync from the SyncInjector as valid, even though the pulse is perfectly >> valid and should be accepted by the PMP450i. >> >> Currently, there are two ways this can be fixed. Since the pulse is >> valid, but just not recognized as valid by the currently shipping PMP450i >> firmware, Cambium could fix this in software. I believe they are >> currently investigating this as an issue, and I honestly expect them to >> release a fix assuming it isn't a major issue to do so. If this happens, >> it should address all of the existing SyncInjectors in the field which our >> customers may want to use in the future with a a PMP450i. >> >> The second way to fix this issue is for us to modify our sync pulse >> slightly so that it is in line with what the PMP450i is expecting. >> Because this modification has some additional benefits beyond better >> interoperability with the current PMP450i firmware (such as the modified >> pulse being less likely to induct noise into adjoining cables), we have >> decided to proceed down this path as well. >> >> During the next week or so, we will begin shipping Revision I0 of our >> Gigabit SyncInjector Product. The first of these are currently working >> their way through our assembly line. This version contains improved >> support for voltages above 58V and also the waveform modification mentioned >> above. It should be functionally identical to the earlier Revision H0 >> SyncInjectors. It is not our intention to update our non-gigabit >> injectors at this time. >> >> If you are currently having problems with sync over power on a Gigabit >> SyncInjector and a PMP450i, please send an email into >> [email protected] and we will work with you to ensure you have >> hardware which will work with your hardware. >> >> -- >> *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* >> Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 >> [email protected] | 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 [email protected] | http://www.packetflux.com <http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux> <http://twitter.com/@packetflux>
