Compiled by G31RM Issue number 24 October 1993 The Newsletter For nearly four years I have been sending out these Newsletters free of charge to those who have expressed an interest. However, photocopying charges are due to increase and postage will increase from the first of next month. I am looking around for a cheaper copying service but do not expect to save a great deal. The total cost of copying and posting the Newsletter was about 235 an issue and is now likely to be nearer P-45. Some of the cost has been met by donations from members, some very generously, but these have not covered the cost so I am afraid I will have to ask for a subscription if you wish to continue receiving the Newsletter. I am suggesting a flat rate of U a year to start with the next issue and I can use dollar bills or reply coupons. This will mean that U.K. members will subsidize overseas members (I send their copies airmail). U. K. postage stamps are acceptable. I did not want to have to do this but there really is no alternative. Where contributions have been received during the past twelve months I have made a note indicating this on this copy of the Newsletter. If I have missed any of you who think you have cash in hand please let me know and I will be only too pleased to accept your estimate of the amount. Computer CCW This is the reason why this issue is being sent out much earlier than usual. I will try and get back to normal times during the next twelve months. I have had two letters regarding my remarks on computer CCW. One of these was from Peter SM6FPC agreeing that a stand4one decoder based on a microprocessor would be a good idea. However, the other letter from Bill de Carle VE210 went a lot further as enclosed was a floppy disc containing a complete CCW package for the IBM computer. To say that I was surprized and amazed was to say the least. I was delighted! He also pointed out where he considers I was going wrong and very interesting his remarks were. As a result there is a lot I have learnt about CCW I hadn't come across before. Those of you who have had a Petft filter operating will have noticed like I did that it is often possible to obtain results over a wide range of settings of the phasing control. This is apparently the case when a good signal is available. Within two or three hertz of the centre frequency the signal is only a few decibels down and infinite rejection occurs at ten hertz. If the signal is very weak, framing has to be optimum within a millisecond or so and the audio tone has to be within one hertz of the correct value. This is where Bill's program scores as automatic correction is made as the program is running. The other side of this Newsletter is an advertisement for this package and the sigma-delta board needed to use the program. I don't know what tests Bill carried out but he seems confident enough to put the program on the market. All I have been able to do is to set up a small low power crystal oscillator keyed for CCW which I receive as a very weak signal in the TS450. Connecting the output of the transceiver to Bill's board and running the program I was able to decode my own sending with very few errors. Bearing in mind that the signal was virtually unreadable under interference this says something for the program. A slightly stronger signal gave perfect copy. What is more the oscillator is not thought to be particularly stable as no temperature stabilization had been included. If you purchase the package you will help greatly in proving its use and you can also purchase the audio spectrum analyser program which Bill markets and which uses the same board. Frequencies have not yet been decided but I have been using 1 Khz up from the QRP frequencies so that QRP operators may hear us but so we will not be on their calling frequency. When more stations are active perhaps we can make a definite decision. Peter Lumb G3IRM, 2 Briarwood Avenue Bury St. Edmunds, Suffolk IP33 3OF England A-k- _X_ C_ W JE:@ fR F:7 C4 t-:- -F- " FR (3 U C-3 1-4 A.E_ - -it i, Producing CD " F-7 F:,-: E7_ " -F " Coherent CW software for IBM-compatible computers 0New DSP receiving filter replaces analog Integrate,,DL[allp clrcUit 0Can Send / Receive standard I(DC)-millisecond CC1W 0Easy generation of CCVJ -frame synchronization preamb1c.--, 0 Precise on-screen freqUency readout Hz) simplifies tuning 0 Automatic fine-tUrlle: centers the S00-Hz CCW tone in tire DSP filter's passband -to within plus Or minus 0.5 Hz 0AUt0MatiC: traffle synchronization and post-sync trac@..-incj 6t5-wUre@-, optimum copy withOUt. need for constant operat-or intervention 0Eliminates need -for expensive Secondary Frequency Standards 0Built-in Beacon mode - can be programmed to send OUt a CCW beacon message at precisely-timed intervals based on GMT aIdeal for LOWFERs --- improves copy off very weak CCW signals even in heavy ORM - really digs 'erri ClUt Of -the noise' Hardware: -IBM-compatible or clone, preferably Turbo-XT or faster (math co-processor is not needed) At least one serial port (COMI, COM21, COM3, COM4) (A Mouse i S USe-FUl , th0Uqh not absOl Utel y reqUi red Sigma-Delta (4" -,., 1.9" external board powered by 9-V battery) This circuit digitizes the aUdio froin receiver s ext sp@.--r jack. and passes the numbers to the software -via one of the computer's serial (COM) ports at 115 K' baud. Described in detail in "Receiver Spectral Display using DSP" (,Jan '92 O.ST), -id Zhc -c i in i : 1991-1 ARRL Handbook:. You don't air eady @ 'You can obtain from VE2IQ at Same time You order COHERENT. Sigma-Delta interface 1.::i-t includes dClUble-@:_ided pc:b Plus all parts needed to build) US 65 Assembled./Tested of above, ready to hook up Li :37 _j COHERENT software package (-3.5" or 5.215" disk, U S Shipping/Handling - all orders. sert Air Mail US Bill de Car-le VE2 I Q 2,3 S C) m al P t V e r t St-Adolphe d'Howard, P Q JOT 2'@Bc) C a n ad a