Author Topic: Newbie question  (Read 665 times)

Offline Warlock

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Newbie question
« on: February 01, 2017, 08:33:16 PM »
Sorry for my ignorance on this but what is a differental reciever board and what does it do ????
Thanks many more newbie questions to come I am sure

Offline Mharnish

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Re: Newbie question
« Reply #1 on: February 02, 2017, 07:06:06 AM »
The differential receivers allow you to run a CAT5 cable from your F16V2 or V3 to the receiver somewhere else in your display, up to 250 feet away from your F16.  Each receiver has 4 ports and you connect a 5V or 12V power supply locally to the receiver.  It allows you to push the data long distances vs only being able to push data 20 or 30 feet from the F16 without the differential receivers.  Excellent way to have 1 F16 in a centralized location and run the Differential boards to locations further away.  Remember you will need a power supply at the location of the receiver as you are only pushing data across the CAT5 from the F16.

Offline JonB256

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Re: Newbie question
« Reply #2 on: February 02, 2017, 09:12:12 AM »
The term "differential" is important here. Borrowing the time honored protocol and wiring system for RS-485, these boards use the twisted pairs of wires in CAT5 cables to get their distance.

The Data output for pixel strings is a single wire format called SPI. Being a single wire is convenient but it limits the distance it can travel before degrading.

The Differential output chip (this isn't just a Falcon thing; other boards are doing this too) takes the SPI signal and converts it to a RS-485 format. That means it now has a Positive version waveform on one wire and a Negative version waveform on the other wire in the CAT5 pair. Using this method, plus the natural noise cancelling benefit of CAT5/CAT5e/CAT6, when the signal reaches the end (the receiver board), the balanced signals are converted back to the SPI signal your pixels need. The two signals error correct themselves even if the waveform has been weakened by the distance traveled.

If you've ever looked at a DMX or LOR output, you may have noticed a + and - mark, because those are Differential also.

Offline jtrpop

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Re: Newbie question
« Reply #3 on: February 02, 2017, 11:40:06 AM »
I'm about to order my first F16v3 with differentials and trying to understand as well. From my understanding the F16v3 will support 1024 pixels per output, but adding differential receivers will lower total pixel output per string. You can add one receiver to the V3 without a differential expansion board though. You can split the 1024 between ports 1-16 and ports 17-32 in 10 node increments. This way 1-16 could be 680 pixels and 17-32 could be 340. 1-16 or 17-32 cannot be more than 680.

Correct?  ;D


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