Narrative:

We have had problems with the rdvs communications equipment ever since moving into the new TRACON 3 years ago. The problem I am describing today is only one of many. We are having problems with receiving 'clipped' xmissions. There are 2 types of clipping we are receiving. 1) the transmission cuts in and out as it is being received. 2) the first part is missing but the rest is clear. I am including 2 floppy disks with 2 .wav files that demonstrate both types. In the wave file for the first type, the aircraft was an MD80 located 10 mi northeast of my receiver's antenna at 13000 ft, in other words, well inside my reception area. This is a frequent occurrence, not just one aircraft's bad radio. It does seem more prevalent if the pilot has a soft voice, but it's not limited to this. In the second wave file I issued an altitude of 'one seven thousand' to an aircraft. What you will hear read back is 'seven thousand,' however, the aircraft climbed to 17000 ft. I have corrected pilots on this up to 5 times in a row and get the same thing back each of the five times. Eventually I just have to give up since asking for the pilot to correct the readback isn't solving the problem. Since the pilot is reading back correctly, they get really aggravated at having to keep repeating themselves. While not the cause of the problem, the problem is exacerbated by the pilot's improper radio technique -- not placing the call sign first. If they would put the call sign first, I would hear '...ompany 123' instead of 'company 123.' while still not correct, this would be tolerable. There aren't that many call signs that are so close in the way they sound that this would be a big problem. The main problem is that we have been complaining for 3 years now and the FAA still hasn't fixed this equipment. Callback conversation with reporter revealed the following information: reporter states that when the new TRACON facility was opened, the old facility integrated communication switching system (icss) was replaced with the new rapid data and voice switching (rdvs) system. The reporter stated from day one, controllers have had receiver problems -- clipped call signs. Aircraft do not experience any controller transmission problems, only controllers receiving aircraft xmissions processed by rdvs. Initially, controller's had rdvs 'call forward' message interruptions, but the problem was eventually corrected by a new path tracing signal. The reporter stated that the TRACON rdvs has three transmitter sites: one at dfw airport and two on either side of dfw airport. All three sites appear to have the same problem. The reporter states that a controller may have 30 to 40 clipped xmissions a shift, causing multiple readbacks to the same aircraft, which adds to frequency congestion and pilot/controller aggravation -- having to respond to so many interrupted transmission readbacks.

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Original NASA ASRS Text

Title: D10 CTLR CONCERNED WITH A 3 YEAR, RECURRENT RADIO XMITTER INTERRUPT PROB.

Narrative: WE HAVE HAD PROBS WITH THE RDVS COMS EQUIP EVER SINCE MOVING INTO THE NEW TRACON 3 YEARS AGO. THE PROB I AM DESCRIBING TODAY IS ONLY ONE OF MANY. WE ARE HAVING PROBS WITH RECEIVING 'CLIPPED' XMISSIONS. THERE ARE 2 TYPES OF CLIPPING WE ARE RECEIVING. 1) THE XMISSION CUTS IN AND OUT AS IT IS BEING RECEIVED. 2) THE FIRST PART IS MISSING BUT THE REST IS CLR. I AM INCLUDING 2 FLOPPY DISKS WITH 2 .WAV FILES THAT DEMONSTRATE BOTH TYPES. IN THE WAVE FILE FOR THE FIRST TYPE, THE ACFT WAS AN MD80 LOCATED 10 MI NE OF MY RECEIVER'S ANTENNA AT 13000 FT, IN OTHER WORDS, WELL INSIDE MY RECEPTION AREA. THIS IS A FREQUENT OCCURRENCE, NOT JUST ONE ACFT'S BAD RADIO. IT DOES SEEM MORE PREVALENT IF THE PLT HAS A SOFT VOICE, BUT IT'S NOT LIMITED TO THIS. IN THE SECOND WAVE FILE I ISSUED AN ALT OF 'ONE SEVEN THOUSAND' TO AN ACFT. WHAT YOU WILL HEAR READ BACK IS 'SEVEN THOUSAND,' HOWEVER, THE ACFT CLBED TO 17000 FT. I HAVE CORRECTED PLTS ON THIS UP TO 5 TIMES IN A ROW AND GET THE SAME THING BACK EACH OF THE FIVE TIMES. EVENTUALLY I JUST HAVE TO GIVE UP SINCE ASKING FOR THE PLT TO CORRECT THE READBACK ISN'T SOLVING THE PROB. SINCE THE PLT IS READING BACK CORRECTLY, THEY GET REALLY AGGRAVATED AT HAVING TO KEEP REPEATING THEMSELVES. WHILE NOT THE CAUSE OF THE PROB, THE PROB IS EXACERBATED BY THE PLT'S IMPROPER RADIO TECHNIQUE -- NOT PLACING THE CALL SIGN FIRST. IF THEY WOULD PUT THE CALL SIGN FIRST, I WOULD HEAR '...OMPANY 123' INSTEAD OF 'COMPANY 123.' WHILE STILL NOT CORRECT, THIS WOULD BE TOLERABLE. THERE AREN'T THAT MANY CALL SIGNS THAT ARE SO CLOSE IN THE WAY THEY SOUND THAT THIS WOULD BE A BIG PROB. THE MAIN PROB IS THAT WE HAVE BEEN COMPLAINING FOR 3 YEARS NOW AND THE FAA STILL HASN'T FIXED THIS EQUIP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT WHEN THE NEW TRACON FACILITY WAS OPENED, THE OLD FACILITY INTEGRATED COM SWITCHING SYS (ICSS) WAS REPLACED WITH THE NEW RAPID DATA AND VOICE SWITCHING (RDVS) SYS. THE RPTR STATED FROM DAY ONE, CTLRS HAVE HAD RECEIVER PROBS -- CLIPPED CALL SIGNS. ACFT DO NOT EXPERIENCE ANY CTLR XMISSION PROBS, ONLY CTLRS RECEIVING ACFT XMISSIONS PROCESSED BY RDVS. INITIALLY, CTLR'S HAD RDVS 'CALL FORWARD' MESSAGE INTERRUPTIONS, BUT THE PROB WAS EVENTUALLY CORRECTED BY A NEW PATH TRACING SIGNAL. THE RPTR STATED THAT THE TRACON RDVS HAS THREE XMITTER SITES: ONE AT DFW ARPT AND TWO ON EITHER SIDE OF DFW ARPT. ALL THREE SITES APPEAR TO HAVE THE SAME PROB. THE RPTR STATES THAT A CTLR MAY HAVE 30 TO 40 CLIPPED XMISSIONS A SHIFT, CAUSING MULTIPLE READBACKS TO THE SAME ACFT, WHICH ADDS TO FREQ CONGESTION AND PLT/CTLR AGGRAVATION -- HAVING TO RESPOND TO SO MANY INTERRUPTED XMISSION READBACKS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.