V.24 wireless????

WB5ITT · Post by **WB5ITT** » Sun Mar 01, 2009 5:51 pm

Right now my company has ~100 UHF Quantars (all running P25) throughout 6 states....all tied to the RNCs and consoles using 56K DDS circuits (a waste since you only need 9600baud).....Some circuits are maybe a few miles from an office with a DDS interface (Excalibar DAP) to the tower where another DAP provides the V.24 to the Quantar...needless to say, these DDS ckts are NOT cheap...one intown for 5 miles is running about $400 a month...is there any reliable (and somewhat low cost) wireless replacements for this?? I have looked at the MDS 900 radios...one of our divisions use them quite a bit but they have 1 5/8in Heliax and 300-500ft sites....I cant justify a major outlay for a tower at the office just to put a 900Mhz SS radio in to talk 5 miles to the rptr tower....(plus the Heliax there and additional rental may make it not worth the effort)..Anyone have any real experience in this and what was your results?

Thanks!
Chris
WB5ITT

SlimBob · Post by **SlimBob** » Thu Mar 05, 2009 12:08 am

I'd go in the direction of a T-1 channel bank (Adtran Total Access 750) and shoot it over DS1 microwave.

JohnWayne · Post by **JohnWayne** » Fri Mar 06, 2009 9:23 pm

You'll need to move up to the Total Access 1500 to get the quad RS-232 access module with V.24. Figure about $800 for the chassis and $300 for the quad RS-232 access module. You'll then need a microwave radio w/ T1, so figure about $11k for a Motorola PTP600 complete link.

Do you have reliable IP connectivity to the tower sites? You can run TDMoIP with a RAD Megaplex-2104 + IP main link module + low speed data module at each tower site, and then another MP-2104 or a larger Megaplex-2100 (if you need more than 16 V.24 connections) at the main site to demux from TDMoIP back to V.24. If you want wireless, then you can use a less expensive Motorola PTP300 ($4k/link) since you don't need the built-in T1. The Motorola PTP radios come in an integrated unit, so you just need to run CAT5 up the tower. Also, you can add a bunch of other interfaces to the Megaplex if needed - they're nifty boxes.

RAD also has something called the Tinybridge-100 which is a Ethernet-V.24 converter, but I think it's the opposite of what you need. It's probably worth a call to see if it can work in reverse.

PM me if you want to get more in-depth with this.

Jeff

FMROB · Post by **FMROB** » Sun Mar 15, 2009 4:36 am

What would you guys suggest for a 4.9 band microwave link that could support 1 four wire circuit and 3 two wire cicuits for remote base use. I was looking at the Carlson sireless equipment which has it own "mux" built in. I have not worked with other styles. If I were to look at the motorola ptp equipment, I would assume that provides a T1 type circuit. What would I need to convert that out to wireline circuits? I would assumed that something like a Adtran Total Access 750 panel might work. How does the channel bank interface into the PTP from motorola?

Thanks, Rob

JohnWayne · Post by **JohnWayne** » Sun Mar 15, 2009 11:12 am

I haven't used any Carlson equipment, but it looks decent enough. We use the Motorola PTP radios extensively all over the world, and even use them as stubs off our Megastar system in the Gulf. They have a 4.9GHz radio in the 400 and the 600 series. The 400 series is nearing retirement, and will no longer be available for order after 30 June 2009. The replacement is the 600 series. Cost-wise, you're looking at about $14k for the 600 with a 5MHz channel bandwidth and integrated antennas, or about $12k for the 400 with integrated antennas. These are list prices and are for the complete link - both ends.

They both provide Ethernet and a T1. As far as interfacing to your remote bases, you can use the T1 interface on the radio with something like an Adtran TA750 with four E&M cards. Expect to pay about $1500 for an TA750 AC chassis with four E&M cards. You will need one at each end of the link.

If you have decent IP connectivity to the site, either through a landline or microwave, then you can use TDMoIP. A RAD IPMux-1E gives you four E&M ports with an IP uplink for about $1500. I've used these with tone remotes, and they work great. Again, you will need one at both ends.

RAD also makes a 4.9GHz microwave link that is in the $4k (list) range with and without T1. It lacks the fancy NLOS and OFDM features of the Motorola, but it's just fine for "easy" shots.

Jeff

FMROB · Post by **FMROB** » Sun Mar 15, 2009 11:40 am

John,

The TDMoIP Rad IP mux ytou are talking about goes over an ethernet link, correct. This would be no good to use for a voting system because of latency type issues??

Regarding the PTP equipment. If the unit says that it has a T1 type connection, I would assume that there is some sort of interface unit that goes inside the shack, if they are intergral antenna-radio units. How do you get from the T1 of the PTP unit to the back of the adtran (channel bank). Is a multi wire connection of some sort?

Thanks, Rob

Sorry about the stupid questions, I just have never used a mux (adtran) before.

Also, What type of punch block would you use to wire in the radio room and 66 or 110?

JohnWayne · Post by **JohnWayne** » Sun Mar 15, 2009 5:04 pm

I've never tried using the IPMux with a voter; it will mostly depend on the latency of your link. Most voter systems can tolerate up to a 100ms delay before things start getting tricky. The latency on the T1 on a PTP600 is ~5ms, and the Ethernet latency is about the same. The manual has extensive latency tables if you're interested. I'm not sure how much overhead the IPMux introduces, but if you have a T1 radio, then you don't need it anyway. The most solid solution would be a PTP600 with a TA750 on the T1 port.

The PTP600 has a T1 port on the radio itself, along with a UTP and fiber Ethernet port. Note that you will need to run a cable for the Ethernet even if you only use the T1 since the power comes in on the Ethernet port. You put the power injector, PIDU in Motorola-speak, inside and run CAT5 up to the radio's Ethernet port. Max distance is 100m. You run the T1 straight into the mux (via lightning protectors, of course) using the same CAT5 cable. It's all really simple once you see it. The provisioning takes about 2 minutes on the web interface, and there's an audible tone as well as a voltage output for aiming.

You can download all the manuals at http://www.motowi4solutions.com/software/. They also have a decent tool called LINKPlanner for, well, planning your links.

As for punch blocks, the 66 is pretty standard, so you can't go wrong with it. A 110 is easier to rack mount, however.

Jeff

FMROB · Post by **FMROB** » Sun Mar 15, 2009 5:34 pm

Jeff,

Thank you. You have been a world of help. I am going to look into the Moto PTP stuff, However the carlson wireless is real easy to use with the E & M mux already built in.

Thanks, Rob

JohnWayne · Post by **JohnWayne** » Sun Mar 15, 2009 6:06 pm

The Carlson is probably fine for "easy" shots. Where the Motorola PTP really shines is near and non line-of-sight shots. I have one shot that is about 4 miles with 30' of elevation AGL on each side and a refinery in the middle. The thing just works. Of course, the 4' dishes don't hurt.

FMROB · Post by **FMROB** » Mon Mar 16, 2009 1:47 pm

Jeff,

Another questions. What type of wire goes between the pidu T1 and the channel bank. Is it similar to a cat 5 cable or a custom piece. Also, on the E & M cards some of the are labled TO for talk out. Is there a difference, or will any E & M card do?

- Rob

JohnWayne · Post by **JohnWayne** » Mon Mar 16, 2009 7:46 pm

The PIDU just goes on the Ethernet port. So, even if you are not using Ethernet, you still have to run a CAT5 cable from the PIDU to the radio. You definitely should hook up Ethernet on at least one end for diagnostics, statistics, and remote configuration. As for the cable, it's outdoor CAT5. I've used the Motorola-recommended armored stuff from Superior Essex as well as Belden shielded CAT5. The main point of the armored cable is the lightning protection properties because the outer conductor is easy to ground with standard ground kits.

Transmit Only (TO) on an E&M circuit means you are just using the audio capabilities and not the actual E&M DC signaling. Most E&M cards I've seen, including the Adtran, will do TO. See http://www.cisco.com/en/US/tech/tk1077/ ... 3f60.shtml for more info on how E&M signaling works.

Jeff

FMROB · Post by **FMROB** » Tue Mar 17, 2009 7:18 pm

Jeff,

So cat 5 goes between the pidu and the card shelf to create the T1 at the shelf (adtran).

Thanks, Rob

JohnWayne · Post by **JohnWayne** » Tue Mar 17, 2009 8:44 pm

It will look something like this:

Adtran----LPU--------------LPU----PTP600 T1 Port

Ethernet Switch----PIDU----LPU-------------LPU----PTP600 PIDU Port

The LPU is the Lightning Protection Unit. Check out page 235 of the PTP600 User Guide for an installation diagram with Ethernet and T1.

The T1 isn't really "created" per se. You could plug your TA750 straight into the T1 port of the PTP600 and it will work. In fact, I recommend completely staging and testing this thing on the bench before deploying it.

Jeff

FMROB · Post by **FMROB** » Fri Mar 20, 2009 1:36 pm

Jeff,

The identical adtran set up is required on both side of a hop if you were to use it for a voting RX site? You would need E & M cards on both sides? - Rob

SlimBob · Post by **SlimBob** » Fri Mar 20, 2009 1:55 pm

More or less.

SlimBob · Post by **SlimBob** » Fri Mar 20, 2009 2:00 pm

The TA750 with E&M cards basically puts the audio into a T1 format. The E&M function (switch / contact closure) provides a way of sending PTT or COS down the circuit. The E&M switch takes over for the hang-up signal on a standard voice line. So you've got voice channels from one TA-750 to another TA-750 over a DS1 line (which may or may not be a full DS1).

Then you insert a wireless TDM system that can carry a DS1 or fractional DS1. It's important to keep the system TDM to minimize delay -- the radios need to be full-duplex (or so fast that the delay is consisent).

When you're voting, you need almost down to DC, or low hertz (less than 3) to make the comparison possible with digital signals.

FMROB · Post by **FMROB** » Fri Mar 20, 2009 3:25 pm

Bob,

You lost me there for a minute. I don't expressly need hard COR or PTT as I will be using guardtone on the voting RX'r, so absence of tone at the comparator will work. If I need to just emulate a lease line (for use with a tone remote base or a voting rx'r) would I then need e & m cards, or would I use a different card with the adtran 750 cage?

Thanks, Rob

Also, you mention TDM. If I were looking to use a moto PTP system that creates a T1, would that be TDM system or somehting different?

JohnWayne · Post by **JohnWayne** » Fri Mar 20, 2009 4:34 pm

Since you don't need PTT and COR, you set the E&M ports for transmit only (TO) mode. At that point, the E&M ports just transmit and receive audio without any signaling. You still need the E&M cards.

T1 is a TDM transport.

Also, for what it's worth, I talked with the RAD engineer at IWCE, and he verified that you can do point-to-multipoint on the Megaplex 2100 and 2014. The IPMux-1E is strictly point-to-point.

Jeff

SlimBob · Post by **SlimBob** » Fri Mar 20, 2009 5:23 pm

I think that the E&M cards would be a better investment given the nature of your business rather than sinking money into two-wire or four-wire cards. The E&M card is basically a four-wire card that uses a single pair and gives you that extra bit of signaling (PTT/COS).

FMROB · Post by **FMROB** » Fri Mar 20, 2009 6:44 pm

Ok, I think that I am understanding this a little better. I greatly appreciate all the detailed answers. It is good anyway to have stuff like this on the forum for everyone to enjoy.

A few more questions though:

1) What would point-multipoint be used for in a radio application?

2) What is the break down and requirements for telco line types. In other words what everyone calls a lease line or tie line what capacity does the give you.

3) What capacity do you need for 600 ohm audio for remote bases and/ voting lines?

4) What exactly are the differences between a DS1, T1, Fractional T1, E1 etc??

5) For example, on a Lynx micrwave radio they list T1 x 2, I assume that it gives you two separate full capacity T1's over the radio?

** 6) In the adtran E&M card you say that it is a four wire card that gives you two wire. I need to run a four wire circuit for the repeater and an additional two wire for a remote base in the same hop, I assume that I would need 3 E&M cards per side, total 6?

7) How many E&M cards will the adtran 750 allow (how many pairs will it support) both in the card cage and over the ptp link?

Sorry for all the questions, But I think that this is it for questions?? You guys rock, Thanks in advance.

JohnWayne · Post by **JohnWayne** » Sun Mar 22, 2009 12:02 am

1. The point-to-multipoint would be useful in a voter situation where you have multiple remote sites and one central site. It saves you the hassle of having multiple IPMux-1Es at your central site. There are other applications, but that's probably the most common one.

2. That question has any number of answers. In the strictest definition, a tie line is a dedicated circuit between two points such as as two phone systems. It doesn't have dial tone since no dialing is required. A leased line usually means a dedicated point-to-point circuit - pretty much the same as a tie line. In the radio world, leased lines are usually "dry", meaning that they have no electronics on the line and are just a straight copper path from point A to point Z.

3. The data rate required isn't a function of the audio interface impedance, but rather the bandwidth of the desired audio. The Nyquist Theorem states that we have to sample the audio at a rate that is twice the highest frequency. For our purposes, we generally only care about frequencies below 4,000Hz, so we need a sample rate of 8,000Hz. For a loss-less circuit (no compression): (8,000 samples per second) * ( 8 bits per sample) = 64,000 bits per second. That's why a DS0 is 64k. A DS1 has 24 DS0s, so 24 * 64k = 1536k/sec of available bandwidth. With the framing bits, we get 1544k/sec. Various compression techniques exist to reduce the required bandwidth at the cost of audio quality. For example, your landline phone line operates at 64k ("toll quality"), but your GSM cell phone uses a 13k codec. To answer your question, just assume you need 64kbps per audio channel.

4. This question is the source of much great debate. T1 is a transport invented by Bell to carry phone lines on the trunk (phone company's) side of the network. DS1 is the actual digital data signal running on the line. Think of it like this: T1 is the physical line, and DS1 is the data format on the line. A fractional T1 is just a T1 with less than 24 channels. E1 is a European (or anywhere but North America and Japan) equivalent to a DS1, except it has 30 DS0s. You can pretty much use T1 and DS1 interchangeably in North America and everyone will know what you're talking about.

5. Yes, you get two T1s.

6. The E&M cards for the TA750 are a single interface on each card, so you will need three per end per link for a total of six.

7. The TA750 has six access module slots, so you can have six E&M circuits per link. The PTP link will handle a whole T1, so you're fine capacity-wise.

Jeff

Q2222A · Post by **Q2222A** » Sun Mar 22, 2009 6:30 am

A quick note of caution. The V.24 signal going to and from the Quantar is a synchronous data signal. Unless you have a data circuit end to end, you are not going to get your connectivity through the PTP links and ADTRAN E & M cards. You need something like a Sub-rate unit or Data type card not E&M cards.

Dennis

JohnWayne · Post by **JohnWayne** » Sun Mar 22, 2009 9:59 am

The topic kind of morphed from V.24 over wireless to 2/4 wire tone over wireless. I think we figured out that WB5ITT needs the Adtran quad RS-232 cards, which do synchronous V.24. See the third post.

Jeff

SlimBob · Post by **SlimBob** » Mon Mar 23, 2009 12:06 am

JohnWayne wrote:The topic kind of morphed from V.24 over wireless to 2/4 wire tone over wireless. I think we figured out that WB5ITT needs the Adtran quad RS-232 cards, which do synchronous V.24. See the third post.

Jeff

Good point. I guess I brought up E&M because that's what comes to mind first whenever linking is mentioned. The TA750 does have an option board that supports V.35, and one that support DDS:

http://www.adtran.com/adtranpx/Rooms/Di ... yJTVEJTVE/

FMROB · Post by **FMROB** » Mon Mar 23, 2009 5:53 am

Thank you all for the reply.

Conversely, If one were using a wireless "IP" based micro link, you would need a rad T1 TDMoIP unit on either end of the enternet link to create a T1. Would this have any drawbacks, such as high latency due to the compression and conversion?

Also, if I needed to do two hops with the motorola ptp to get around a obstruction, is this possible? How is this done.

I could see if you were using only the ethernet I guess you could use a switch at the intermediate hop point, but how would you link the T1 to T1?

Thanks, Rob

Post by **/\/\y 2 cents** » Thu Mar 26, 2009 4:22 pm

Folks,

The RAD unit works. Ive used it for voting applications as well as V.24 and V.35 to PCM/T1 sctructured and then to DSL and CBl modems. I actually have been OEM'ing them and providing support to radio folks who are IT/circuit learners, helping them evenly adjust comparitor delay varible adjustments, help them stop blaming the Internet for what they dont understand yet, etc.

The only thing is the Motorola Canopy Ethernet radio units/modems dont work too well because they are use TDD vs FDD which can lead to high loss in CBR (Constant Bit Rate) applications such as tying to emulate a circuit with a guard tone, etc. Try Proxim for FDD and best results in these demanding legacy enviornments. Amazing how many folks never discover this until they start trying to use them for sweeter apps that save more $

You can actually get away with a cheaper box than a IPMUX11 or VMUX for just transporting V.24. These units do all and EVERY type of serial over IP. These would be better because it sounds like you dont need the voice portion if it is just a serial pattern being encapsulated and transported.

Anyways need info just ask.

Regards,

Steve

www.criticalrf.com

FMROB · Post by **FMROB** » Sun Apr 12, 2009 6:52 am

If I have three separate micro hops terminating at one master point (where the voter is going to be located) do I need three separate adtrans at the master site, or can I use one adtran to connect to the three T1's and then break it out to E&M modules? - Rob

SlimBob · Post by **SlimBob** » Sun Apr 12, 2009 9:12 am

You'd just need one at the master site.

FMROB · Post by **FMROB** » Sun Apr 12, 2009 2:02 pm

How would I do that. How many separate T1's can the adtran 850 handle? Rob

FMROB · Post by **FMROB** » Wed Apr 15, 2009 6:47 pm

Bump... Any luck on this.. Thanks, Rob

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