Machine-to-machine Tetra
the exhibition hall was Funk- Electronic Piciorgros, of Cologne, a specialist in radio modems and telemetry products for control and monitoring applications using GSM and Tetra. Latest innovation from the
P
“This is unique”, says Cindy Mayerhoff, an engineer with Radiodata. “This is DMR in four metres and duplex, so that you can talk at the same time, like you know from the telephone. And we have base stations. They work in Tier III and Tier II”
Full duplex DMR A
mong other companies featuring DMR technology
at PMRExpo was Berlin-based Radiodata, which offers Tier II and Tier III equipment under its Dipra (‘Digital Professional Radio’) brand. Unusually, the range include products for the under- occupied lower VHF frequencies as well as for high-band VHF. UHF radios will soon be added. Radiodata’s Tier III technology has already been supplied to public utility customers in two counties in Germany. “We have a whole range
of systems here”, said Cindy Mayerhoff, on the company’s stand. “We have mobile radios in the four-metre range and duplex, and we are the only ones who’ve developed this. You can’t fi nd it anywhere else yet. “And then we have a switch
which is an interconnect to the telephone system and IT system, and also does the network management. You can set up groups, like you have in Tetra. “And I forgot to tell you – the
base stations are single-site and simulcast.”
company is a compact Tetra radio card, developed in-house. “T is makes us independent from oth- ers, because we started with exter- nal modems and we fi xed some bugs and we did research for them”, explained r&d engineer Dirk Reufsteck. “But we wanted to have it in our own hands, so now we have the knowledge, we have the product. If we have to change something, we can do it on our own – we don’t have to ask whoever.” One such development Picior-
gros has already implemented is a simplifi ed alternative to some of the rather complex command language used for controlling radio modems – for example, for the common requirement of initiating a packet data transfer. “We said, why is it that com-
plicated? It’s just to enable packet data, that’s it. And so we made a
ossibly the company which had the shortest journey to make to
Dirk Reufsteck, development engineer at Piciorgros, with a Tetra-enabled industrial controller and, at left, the company’s new Tetra card
command to enable packet data and then our modem gets this command and it enables packet data. And that’s everything.” Another problem solved by the
board, he said, is that some Tetra base stations are apt to ‘forget’ telemetry devices after 30 minutes if they do not transmit frequently. “We had this problem and we solved it with implementing in our Tetra stack to send a packet to the base station. So maybe we fi xed some base station bugs! We recog- nized it, and it was half a day!”
Technology for bigger DMR systems M
otorola Solutions is not at present offering DMR
Tier 3 support in its MotoTrbo DMR product family but instead has two system enhancements for implementing larger digital systems – IP Site Connect, which allows the linking of up to 15 repeaters at one or more locations, and Capacity Plus, a single-site trunking capability. On the company’s stand at
PMRExpo, DMR Direct Mode operation and Capacity Plus repeater operation are being demonstrated to show visitors by Wolfgang Meier, whose normal job is providing hotline support for Motorola’s network of dealers in Germany.
14 “I think I think you have heard
something about DMR”, he begins. “DMR has two timeslots, each with 30 milliseconds, but only with 12·5 kHz [channel] spacing. This repeater is able to work in analogue mode or in digital mode. It’s the same with the portables: unlike with Tetra radios, here you can select an analogue channel. So it is possible to have fi rst your standard analogue system with the old radios – maybe it has to be on the same frequency, VHF or UHF. Then, one day you can buy all new radios and work with analogue. And then one day you can change them all to digital.” Picking up a handful of
handportables, he continues: “These two are calling a group call on the fi rst timeslot. And now I’m opening a new call and I’m automatically on the second timeslot. With Capacity Plus you can stick up to six repeaters, a maximum of 12 slots, and you have an automatic rest channel. The radios which are next speaking will automatically be pushed on to the rest channel.” Capacity Plus can link up to
six MotoTrbo repeaters at a site, adding the ability to support as many as 1200 users.
Professional amateurs Mr Meier adds that IP Site Connect has already received a
able to access the system remotely from home via their broadband Internet connection. If the remote stations know the address of the master station, the whole system can confi gure itself automatically, updating the list of radios that are in the network. “It’s a very simple system”, Mr Meier observes, approvingly.
LAND mobile January 2012
full workout behind the scenes at the hands of Motorola’s amateur radio club, whose members interconnected as many as 20 DMR repeaters. “But for using all the features the system has, you have to have not more than 15”, he cautions. Club members were also
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