Need help with a project that's been stumping me for 5 years!

[Raynentye]

Let me start off by saying that I didn't know where to post this so I figured this would be ideal and then you guys could point me in the right part of the forum to jump to.

I've dealt with business band radios for 12 years; Motorola, Kenwood, Icom, Relm, Bendix/King, etc. I have an electronic engineering background, and I'm still a technician. I have NEVER dealt with HAM radios of any type and I now regret it.

I have been working on and off on a project for the past 5 years. As with everybody, money and time play important factors when trying to complete projects, for which I've had very little of both. My apologies if I'm a bit long winded, but being my first time on this forum, I feel it should be an introduction of sorts.

My project involves a panel with an RS-232 output that would normally be connected to a serial printer (Yes, they still make them) and my necessity to be out in the field while monitoring and maintaining this piece of equipment. Unfortunately, it isn't always in the same location, at times these panels will be located in an industrial area, or an office area, or a school or may even be in separate buildings than where I need to be. Normally, it takes two people with two-way radios to work on this equipment. However, that is a luxury I'll soon no longer have. Instead of fixing something only to come back to the main control panel to find there's another problem, or I didn't fix the problem to begin with and have to go back out to the problem area, I'd like to connect a wireless transceiver to the main control and carry another one with a small screen to mirror exactly what the control panel is showing.

I've had some minor success with Digi's XTend Radio Modems:

XTend RF Modems - 1 Watt/900 MHz Stand-Alone Radio Modems - Digi International

But I don't think 1 watt is working so well in most of the environments.

I see many other Radio Modems on the market for SCADA control like Kantronics Talon Data Modem:

Kantronics Talon Data Radio

But this particular unit is about $1200 a piece! That would be a minimum of $2400 just to get me started! I like the idea of the multiple inputs and outputs as well so I'll be able to have some rudimentary control of the central unit, but I wouldn't be able to afford that for another 5 years!

As I was searching for the terms Radio Modem and Data Modem, I stumbled upon Data Radio Telemetry (DRT) and Automatic Packet Reporting System (APRS) that use Terminal Node Controllers (TNC). It took me a day or two to process but I've gathered enough information to be dangerous. Yet I have many questions but it seems most of the HAM forums are locked down and only those with call signs are allowed to join. I was quite happy to find this one that allowed the average me to co-mingle with the hardcore guys and maybe find some answers.

Now, this is really your standard RS-232 port with simple settings like 2400 to 9600 bps, 7 to 8 bit parity, 1 stop bit, . Even and no Control. Some units are different and use different settings. I was either going to use a serial LCD screen or a Ultra Mobile PC (UMPC) like the OQO running HyperTerminal. All in all, its a serial cable replacement. I assumed it was no big deal and should be fairly simple. But, I was wrong.

So, here's a few of my questions: Could I use a couple of Motorola CP200 portables, and two TNCs? If so, which TNC would be recommended for fast and simple operation?

Is there a 4 to 5 watt Data Radio that can take the place of both the portables and TNCs that is still relatively inexpensive (ie: around $1k for a complete set)?

OR should I go get my HAM License (I'm going to anyways) and buy a couple of portables like the Kenwood TH-D72A and somehow connect one of them to the panel and use the other one as a receiver and screen all in one? Or get one TNC, a radio, and a TH-D72A?

Oh man, I'm so confused I have a headache! Any help or direction would truly be appreciated!

 

[canav844]

OR should I go get my HAM License (I'm going to anyways) and buy a couple of portables like the Kenwood TH-D72A and somehow connect one of them to the panel and use the other one as a receiver and screen all in one? Or get one TNC, a radio, and a TH-D72A?

Oh man, I'm so confused I have a headache! Any help or direction would truly be appreciated!

Well you can't use the HAM bands for work so that's not the reason to go that method; but you can use TNCs and AX.25 Protocol on Non HAM bands, if you're licensed which it sounds like your company may have a license that they could get a frequency to use for this purpose.

I believe most APRS is going on at 4800bps, for the really good breakdowns on the packet structure look into the Amateur Handbooks or the ARRL's VHF digital handbook, the technical side is the same even when the application is non commercial. DB9 to R232 type port should be relatively accomplish-able.

As for Radios, it's all going to depend on your range, because without an amateur license for business work you won't be able to utilize the network on 144.39, so you'll have to do direct or setup your own network; If you have some VHF Frequencies and go to Argent Data's website they'll be able to sell you, TNCs Cables and Puxing PX-777 5 watt Part 90 (VHF Business band) that not needing GPSs would go for about $100 before the computers to handle the data and software to make sense of it or so for the package, make your base station at the control point, have a good antenna location and decent power and you may find communication ranges in a 10mile radius, and you can make that even more if you setup a third radio in the vehicle that gets you to the work site to digi-peat the datapackets. Again you can't use amateur radios or frequencies to do this, but business frequencies, licensed for data with any part 90 FM radio and TNCs that amateurs frequently use, should be ok.

I'm not Familiar with DRT or what that would take to implement.

I'd encourage you to get your ham license, since you appear to have the aptitude to do so and it's fun, you'll learn more about radio and be able carry over the knowledge gained, but you cannot use it for business purposes, just pleasure.

 

[ipfd320]

with his knowledgeable background he will pass the general no problem as what i just read

 

[Raynentye]

I just noticed a few other things on the net... Software TNC... I assume it would be possible to use two computers as opposed to two TNCs. OR use one TNC at the head end and TNC software on the field computer. I have an OQO Model 02. It'd be much easier to carry the OQO and a Portable, than trying to attempt to carry a portable (easy, just use the belt clip), a TNC, and the OQO. The TNCs I've seen aren't very pocket friendly. Actually, I saw the HeathKit HK-21 Pocket TNC, and the PacComm HandiPacket... But neither one of them said anything about the port speeds. I assume with a "Store and Report" TNC, communication speed between the TNC and radio don't make a difference. Or the TNC and the User Interface either. As long as the TNC can match and read the equipment, the send speed shouldn't make a difference, right?

Honestly, I know nothing of this stuff. I mean, the TNC essentially acts as a modem interface, of that much I get, but with TNC software, do I need any particular hardware, or could I just plug the radio into the Mic and speaker input of the computer and the software emulates the rest? I'll try to research this further on my own, I'm no pushover! But your expertise would be great! Oh so many questions though!

 

[Raynentye]

I'm not sure what happened, but I wrote a post prior to the one above. Thank you for the info canav844. I'll not be using HAM bands. Our company is licensed in the 460 MHz business band. We have 4 frequencies. We use one for primary voice traffic, another for an alternate or two man teams on the same location and a third for inter-agency communication. The fourth is free which is probably what I'll use. I own a couple of Relm RPU3600 portables and a Relm mobile unit. I could set up the Mobile with a digipeater (Once I figure out how that works!), and the portables for standard operation. As I mentioned above, I'm a little unsure as to what TNCs I should use. Or, if I should use a TNC for the field unit or use a program instead. Any thoughts?

 

[GrumpyGuard]

I would get in touch with Ardent Data and talk with the owner. If he can't help you set up your system he will more than likely put you in touch with some one who can. His customer service is top notch. He will be able to explain the TNC and how to packet system works. Another good in-expensive radio is the Wouxum line of radio's.

Good luck with your project.

 

[Raynentye]

Thanks GrumpyGuard. I had email correspondence with Mr. Scott Miller (of Argent Data Systems) earlier this week pertaining to his UHF FC-301/D data radio he sells. I was hoping it was what I was looking for. He was the one that pointed me to Kantronics' line of TNCs. That's pretty much why I signed onto this forum in the first place; to learn more about TNCs and how to incorporate them into my needs.

I have learned a lot in the past 24 hours from just trolling the net. I still have yet to research computer software dependent dongles, but it seems I've taught myself as much as I can without having a specimen to physically work with. I now know when TNC sellers advertise a 9600 bps TNC such as the TimeWave PK-96, they're referring to the actual transmit speed from TNC to Radio. From terminal to TNC seems to be adjustable for the needs of the terminal itself. That is precisely what I need. I doubt it matters if the transmit speed is 300 bps (which I gather was the original standard for TNC speeds) to 192k bps (which seems to be one of the fastest to communicate to satellites). As long as the terminal is happy, I'm happy.

As for which TNC to choose from, I'm a might bit unsure of that. You see, I was looking for AX.25 protocol but then KISS started to confuse me until I discovered that KISS is merely a variant of the AX.25 protocol; and all the AX.25 protocol is, is the communications and programming format of the TNC itself.

Whew! I'll tell you, I think the name Amateur Radio should be changed to Professional Radio! There's no way I'd be able to get my HAM license studying before the next test! Which is April 2, locally.

But in the meantime, I still need some input about which TNC any have chosen. I am looking at portability like the HeathKit HK-21, the PacComm HandiPacket, or the PacComm PicoPacket.

Trying to find them on the internet seems near to impossible. Are they still in production? Are there any similar units that boast portability such as these?

 

[rvholland]

Just thought I'd throw in some more things to consider. I think I understand that you're trying to remote a serial async terminal or printer. It also appears that you need 9600 bps in your application.

APRS would not really be applicable for this as its really an application layer that runs on top of AX.25 to do something different from what it sounds like you want to do.

The Terminal Node Controller used by many amateur radio operators to build out APRS networks is capable of providing other options for data transmission however. In the 80's many hams operated packet networks with these TNC's. These TNC's can be setup to operate in a "connected" mode where two TNC's connect with each other over AX.25 and a half-duplex radio connection. This allowed keyboard chatting between the two operators over the packet network. The operators would use a real terminal or PC based terminal program connected to the TNC. As they typed the the characters were sent to the TNC and buffered up until a certain amount of data had been buffered or the carriage return character was seen. The TNC would then send the data via AX.25 and the 1200 bps modem chip in the TNC via the radio to the other TNC. The data was sent as packets and error checked so that whatever was sent was known to arrive at the other end.

The packet protocol and its error checking sometimes will have to resend data due to errors in the received data that occurred on the radio link. This resending is automatic when the TNC is "connected' to the other TNC. So in the typical ham application with a TNC we have a rf link running at 1200 bps with the TNC connected to a user terminal program at either 4800 or 9600bps async. The TNC will buffer data from the terminal program but there's only so much buffering that can be done before we run out space for data unless that data stops every so often. For this the TNC uses flow control to hold off the terminal program.

So a couple of typical ham TNC's connected to a couple of radios and setup in connected mode could pass RS-232 serial data like it sounds like you're after. You would have to be willing to deal with effective max data rate of 1200bps though.

It is possible to get TNC's capable of sending data over the radios at 9600 bps but the radio to TNC connection is different in that you need to bypass part of the audio output stages and have a discriminator tap in effect. The 1200 bps connections can be made via mic and speaker connections. Some VHF/UHF ham radios have special interface ports that provide the 1200/9600 connections while others don't.

Keep in mind that even with a 9600 bps rf link there is still overhead form the AX.25 protocol that along with possible retransmit from link errors that will require you to utilize flow control at the terminal side.

Like was earlier mentioned though using the ham bands for this as a commercial application is not permitted. I don't know if the use of AFSK data on your service is permitted either so I'll leave that for you to consider.

Kantronics still builds TNC's like this. The KPC3+ is a 1200 bps unit and the 9612 is capable of the 9600 data rates as well.

Hope this is helpful.

 

[SCPD]

I'd like to connect a wireless transceiver to the main control and carry another one with a small screen to mirror exactly what the control panel is showing.

I'd connect it to a cheap computer with Internet access or a phone line. Remotely dial in if modem. If it has Internet, run SSH on your smart phone to remotely log in and examine the panel output. A simple logging application can dump the output to a file and email it to you or hold it until you can use secure FTP to retrieve it. Worst case is you put a 3G wireless modem on the box (eg. Clear Data).

Throw down box is $50 to $100 (free if you have one).
Wireless Internet is around $50 a month (only necessary if the remote site isn't "wired" for Internet).

I doubt any two-way solution will be as cost effective.

 

[Raynentye]

Hi rvholland, I think we're on the same page. Yeah, I got the feeling that APRS was one way to use TNCs.

As it is, I'm not so worried about the speed at which the info gets to my terminal, I'm more concerned if it gets there at all! Some of these units report at 4800 bps and most of the newer ones report at 9600 bps. The fact that it actually has to be slowed down in order for the radio to listen and transmit all the data is fine with me.

Granted the TNC's buffer will fill rather quickly, but that's a given. Most serial printer buffers are only 128kb to 256kb anyways. The unit only sends one 80 character line at a time. As long as the info gets to the terminal, the buffer should dump accordingly... I think.

I absolutely will not be using HAM frequencies. I don't have nor do I have access to any HAM band radios. But I'll be sure to buy a few once I get my callsign! But it really does seem like I have so much to learn! At least I don't have to try to memorize Morse code anymore!

As for AFSK data on the business band, I believe it falls under Part 90 where it says, "or remotely monitoring and controlling equipment." However, before attempting this project, I'll contact an FCC rep.

Why do I get the feeling that TNCs are going by the wayside? APRS seems to be all the craze and I'm finding that they're the only current projects out there using them. That and Digipeaters for APRS systems. Has broadband/wireless broadband internet taken its place? The only other application I've seen TCPs in use is SCADA monitoring and control. And those things are in the thousands of dollars range.

It looks like Kantronics is rather "Cream of the Crop" type stuff. I've seen the KPC3+ for $400+ and the 9612 for $800 and up! I'm thinking on maybe getting a couple of PacComm PicoPackets. The both of them should cost a little under $400.

Anyone experienced with the PicoPacket? Are HAM TNCs no longer used anymore?

 

[Raynentye]

I'd connect it to a cheap computer with Internet access or a phone line. Remotely dial in if modem. If it has Internet, run SSH on your smart phone to remotely log in and examine the panel output. A simple logging application can dump the output to a file and email it to you or hold it until you can use secure FTP to retrieve it. Worst case is you put a 3G wireless modem on the box (eg. Clear Data).

Throw down box is $50 to $100 (free if you have one).
Wireless Internet is around $50 a month (only necessary if the remote site isn't "wired" for Internet).

I doubt any two-way solution will be as cost effective.

Hey Unittrunker, unfortunately, I wish I had a smartphone. I have a Nextel Blackberry Curve with no data plan. Heck, I don't even have text messaging on it! My boss is a little under the curve (no pun intended) when it comes to telephony technology. He swears by Nextel's spotty coverage and dropped calls. Actually, he likes the two-way feature, whereas, everyone else in the company hates it. Sounds kinda funny coming from a guy who wants a HAM license, but I've really had it with Nextel!

I do, however, have a wireless broadband service (Verizon) that I personally pay for. But that would mean I would have to pay for another one. I did contemplate this, though.

I was planning on using an Arduino with a SIM shield and a prepay plan SIM. The Arduino would be connected to the panel and, once powered and reset, would call into my web server back home. From my OQO, I'd log into my web server as well, and be able to pull up what the panel was doing.

Alas, if a port setting needed to be changed, I'd have to reprogram the Arduino. Granted, they're rather cheap at $35 and I could have one per setting, the SIM Shields aren't cheap at $140 a pop and the prepaid data plan of 2Gb would probably be eaten up before the month's end. Call me old fashioned, but I hate monthly fees. I'm compromising with my wireless broadband, but the boss doesn't give me many options when he doesn't want to pay for it and he also wants emailed reports while I'm on the road.

This little pet project of mine was conceived many years and three companies back. Even then it was an Ad-Hoc connection that I dreamed up. I'd like to see it come to fruition as such. I was thinking of using a bluetooth serial radio I have to connect the TNC to the BB Curve. But I don't know of any terminal programs for the BB. Besides, the bluetooth connection is just another power hog. But it just might be possible...

Until the day that my boss realizes how awful Nextel is, I'll have to go the Ad-Hoc route. But I do dream of the day he hands me an Android powered phone and saya, "I just don't know what I was thinking!" And then the real fun of forcing this company into the 21st Century begins!

 

[kb0nly]

I'm a little late to join the convo here but i have a couple questions...

So if i understand this correctly, you have a RS-232 (serial) port that is outputing text to an old fashioned printer at one location, you want to take that output and instead transmit it to be monitored remotely, is that the jist of it?

Argent Data's Opentracker+ can be firmware loaded to operate as a cheap KISS TNC, i have used them in this manner many times now. Then you would use one at the terminal location to transmit data received and at your remote location you would have another Opentracker+ and a laptop or other terminal device to display the output. The only thing i am not sure of here is how to make the input to the Opentracker+ at the terminal location transmit a continuous stream of the info, this could be answered by people who are smarter with AX.25 protocol. The Opentracker+ is small, lightweight, and can run off a 9v battery for a long time though, so it would fit the bill for portability.

You didnt mention the actual average distance, feet, hundreds of feet, thousands, miles, etc... So that makes a big design consideration as well obviously. I have used some of the wireless serial extenders commercially available, most of which make it a few hundred feet, some a bit more. Some of them you could actually take apart and replace the transmitter and receiver module with a higher powered unit, such as a 5w HT with a little hackery. Just realize then that the radio at the terminal location would be transmitting a lot and would likely need an external source of power as the battery won't last long at full power continuous, and also HT's aren't rated for continuous transmit either and will get hot, etc.

 

[rvholland]

I mentioned the buffer issue because if the incoming characters arrive at a rate faster than the TNC can effectively get them to the other end buffers will fill to the point where the TNC will need to invoke flow control on the incoming data, typically via RTS/CTS hardware flow control. The serial printers you mention likely could do this too if there is a danger in the printer of overrunning its buffers.

TNC's were the building blocks for hams to build their own packet networks before the internet came about. There was work in TCP/IP networking and one big application was the build-out of DX spotting systems where hams would share info on DX station they were working. The internet has displaced much of this use. As a result of this displacement you can sometimes find TNC's at hamfests but some of this scarcity keeps their prices up a little.

New Kantronics units are available at many online ham vendors. I just looked at hamradio.com and they show a KPC3+ at @ $200 and the 9612 @ $400. My experience is with Kantronics so I can't address the other units you mention.

Another reply mentioned firmware for the OpenTracker operating in KISS mode. The Kantronics is also capable of operating in KISS mode as well as it ships. However I don't think that will do what you want. KISS, colloquially called Keep It Simple Stupid, is an operating mode where most if not all of the AX.25 protocol is bypassed in the TNC and moved up to the program running on a PC. This allows certain applications to implement APRS and have better control of what is going on.

A TNC operating in KISS mode, as I understand KISS, will not give you the capability to "connect" to another TNC and have the serial link capability I think you're after. You can think of the "connect" mode as a application program running in the TNC to take your serial traffic and send it to the other TNC via the AX.25 protocol. In KISS mode you would need to give the TNC AX.25 packets all ready to go but you don't have that capability with serial data from a RS-232 port.

Perhaps the other poster can expand how that would be done in KISS mode. As I understand your desire there would be a serial port sending data and this is not necessarily a PC you can run a program on. This port would connect to a TNC and then a radio.

KISS is good. I operate my KPC3+ in KISS mode at times but I have a program on the PC that is doing the AX.25 work which is common in APRS applications.

 

[Raynentye]

Well, I ordered a couple of PacComm PicoPackets and they should be in my hands by Tuesday. I've yet to get the connectors to adapt the business portables to them, but I'm confident I'll be able to get them working.

Also, I passed my Technician Element 2 test this morning and am now waiting for my callsign! So, I suppose I have a busy week ahead of me. I'm going to be studying for The General Element 3 to be ready for the next local testing cycle. Hopefully, I'll be holding an Extra License within a year. Maybe I'll gain a bit more insight hanging around the local Amateur Radio club.

I'll post my results soon enough! Thanks guys!

 

[GrumpyGuard]

Congratulations on your ticket. Welcome to the ranks of Amateur Radio. A whole new world has opened up for you. With your engineering background the General Test should be a breeze.

 

[Raynentye]

Thanks GrumpyGuard! I'll see what happends in June!

So, I bought 2 PacComm PicoPackets. I've been over the instructions a few times and tried contacting PacComm but they're not responding.

I'm having troubles attempting to wire the radios to them. I have a CP200, and a few Relm RP3600U Portables (Sort of like the Motorola EX500/600. Same connection type).

The PicoPackets have the following connections:

5- RX Audio Input (Radio Speaker)
4- PTT utilizing open drain keying pulled up to positive (I assume it can be connected to a normally open switch and closes on PTT)
3- Ground (This is obvious)
2- TX Audio (Radio Microphone)
1- R-PTT (connected to an internal 2.7K ohm resistor. It would be tandemly connected to TX Audio. I kind of understand this)

The CP200 connections are as follows:

2.5mm sleeve: Ground (Blue)
2.5mm pin: Microphone (White)
3.5mm sleeve: Positive Speaker (Red)
3.5mm pin: Negative Speaker (Black)

The RPU360U connections are as follows:

Pin 1: Positive Speaker
Pin 2: Negative Speaker
Pin 4: Positive Microphone
Pin 5: PTT/Negative Microphone
Pin 7: Ground

How would I go about connecting them? Is it even possible?

I'm so close!

 

[Raynentye]

Success!

I have succeeded in bench testing! Instead of using the two radios listed above, I purchased a couple of Wouxun KG-UVD1Ps using our company licensed frequencies, and tweaked a few of the Pico Packets' settings and Viola! I can't believe how easy it really was!

The KG-UVD1Ps are a pretty good radio! Quite ideal for a beginning HAM Radio Operator such as myself. Very simple and intuitive to use. Quite a wide TX and RX range! Not too powerful to cause harm so its great for practice! I haven't tried out the HAM bands other than monitor the APRS frequency to hear how those packets sound.

But that's pretty much the short of it! I thank everyone for their help!