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Old 04-15-2012, 02:26 PM
jpeskin jpeskin is offline
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Default Bridge distant SNAP networks with a long-haul serial RF link and DS_PACKET_SERIAL?

We have an application where there may be multiple clusters of SNAP networks that are spread across a large facility (anywhere from 2000ft to 1mi-4mi+ between SNAP clusters). I have found with the modules we are testing (ZICM2410P2) that we will be lucky to get 300-500ft at max power using the built-in "F" antenna. Installing many nodes between clusters is not a cost effective option and power is not always readily available.

In the SNAP Reference Manual it says you can configure a node to use the Packet Serial protocol over a wired UART via:
crossConnect(DS_UART0, DS_PACKET_SERIAL)

My idea is to bridge distant SNAP networks using a long-haul wireless serial port link. My hope is that as far as SNAP is concerned, this will seem as a wired serial link, and just a standard connection to another mesh node.

1. Do I understand correctly that DS_PACKET_SERIAL means a node can be communicating with a local SNAP network over its built-in wireless link, while simultaneously communicating with another node over a wired UART? (as if the wired UART were just another mesh hop?).

2. Will it be feasible to link two distant SNAP networks using a long-range (high power, directional antenna) serial RF modem that is installed at each SNAP cluster? The modem would be connected to a SNAP node that makes use of the crossConnect with DS_PACKET_SERIAL option to talk to the distant SNAP mesh network as though it was a wired UART connection, even though in reality it is an RF serial port.

3. If this is possible, is this architecture "transparent" in that we can simply bridge multiple distant SNAP networks in this way, but program each node as though they are just one large SNAP network? (except of course for the special bridge nodes that must be configured to use DS_PACKET_SERIAL).

Thanks,
Jonah
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Old 04-16-2012, 01:45 PM
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gvoce gvoce is offline
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1. Do I understand correctly that DS_PACKET_SERIAL means a node can be communicating with a local SNAP network over its built-in wireless link, while simultaneously communicating with another node over a wired UART? (as if the wired UART were just another mesh hop?). Yes, DS_Packet_Serial is a Synapse Packet Serial protocol that you can route to different interfaces like a UART. You can also use the cross connect command to automatically route data from say a UART to transparnet mode (wireless) and transparent to UART. There is a table in the SNAP reference manual that gives you the different options.

2. Will it be feasible to link two distant SNAP networks using a long-range (high power, directional antenna) serial RF modem that is installed at each SNAP cluster? The modem would be connected to a SNAP node that makes use of the crossConnect with DS_PACKET_SERIAL option to talk to the distant SNAP mesh network as though it was a wired UART connection, even though in reality it is an RF serial port. Why not just use a RF module with an external antenna that you can then attached whatever antenna you desire. You are adding a RF modem to the network just to get data to the next set of nodes ??? I would suggest an RF100 or RF200 with an external antenna. Let the nodes hop the message for you if the other group is out of range. I think we need to address why you are only getting 300 - 400 ft range.

3. If this is possible, is this architecture "transparent" in that we can simply bridge multiple distant SNAP networks in this way, but program each node as though they are just one large SNAP network? (except of course for the special bridge nodes that must be configured to use DS_PACKET_SERIAL). yes I believe what you are trying to do is fessible but seems like a lot of work and hardware. I would address the range issue. The RF100 or RF200 external RF modules I believe will give you better range than what you are seeing.

http://www.synapse-wireless.com/snap...ents/rf-engine
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Old 04-16-2012, 07:34 PM
jpeskin jpeskin is offline
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Thanks for the thoughtful response, gvoce:

Quote:
Originally Posted by gvoce View Post
2. Will it be feasible to link two distant SNAP networks using a long-range (high power, directional antenna) serial RF modem that is installed at each SNAP cluster? The modem would be connected to a SNAP node that makes use of the crossConnect with DS_PACKET_SERIAL option to talk to the distant SNAP mesh network as though it was a wired UART connection, even though in reality it is an RF serial port. Why not just use a RF module with an external antenna that you can then attached whatever antenna you desire. You are adding a RF modem to the network just to get data to the next set of nodes ??? I would suggest an RF100 or RF200 with an external antenna. Let the nodes hop the message for you if the other group is out of range. I think we need to address why you are only getting 300 - 400 ft range.
Yes, this is an option I am also exploring. But the RF100/RF200 are still somewhat limited in power output (<20dBm or <100mW). Whereas there are COTS 900MHz modems that can legally output 1W of power and that's before the option of an external high-gain antenna (pre-certified) to get to 4W of effective power (claimed 40mi link range). For absolute maximum legal range, I don't think any of the existing Synapse modules are there even with external antenna.

Another problem with a RF100/RF200 with external antenna is that this configuration will legally require FCC testing (unless Synapse has shown FCC compliance with specific high-gain directional antennas, which I don't believe they have--only with isotropic antennas). Whereas some serial modem mfgs have already shown compliance with a variety of high-gain directional antennas.

Also, should we wish to sell the products into other countries, by using an external serial modem, we can simply buy COTS whatever RF serial modem complies with the limitations of that country. With RF100/RF200 we would need to go through compliance for various countries in which we wish to sell.

With that said, I agree that it may be worth exploring certifying an existing module in combination with a high gain antenna. That might just give us enough long range performance for most scenarios.

Quote:
Originally Posted by gvoce View Post
3. If this is possible, is this architecture "transparent" in that we can simply bridge multiple distant SNAP networks in this way, but program each node as though they are just one large SNAP network? (except of course for the special bridge nodes that must be configured to use DS_PACKET_SERIAL). yes I believe what you are trying to do is fessible but seems like a lot of work and hardware. I would address the range issue. The RF100 or RF200 external RF modules I believe will give you better range than what you are seeing.
I definitely appreciate this suggestion, and agree that it's a good option. But again for international installations, and for getting absolute maximum legal range in every country, it would be a huge peace of mind to know that if we had to, we could solve the bridging of two distant SNAP networks using a COTS serial modem.

It would be nice to have at least theoretical confirmation from Synapse folks that this should work in theory, if no one has yet tried it in practice.
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