[digitalradio] Re: Direct RTTY Generation
In your MMTTY folder (the one that contains the file mmtty.exe), is the file extfsk.dll present? No. n fact that file is nowhere to be found on the machine at all :-( So guess I need to go back to your download page and find it. Its all getting too complicated - the design was a request for a simple Tx for beginners that wasn't yet another CW QRP transmitter - and I was hoping RTTY would be as dead-simple to get going as it used to be back in the days of yore. Clearly not. It might even be easier to wrirte my own simple RTTY Tx terminal in VB6. Waggling the TXD line using the MSComm1.Break = True/False function will do the job if timing can be assured. And to the others who made comments - Setting the shift is part of the self education process - I suggested they use Spectran or SpecLab on thre output on an SSB Rx to set up the shift at test. Only a case of tweaking a preset R FeldHell or whatever isn't an option. Its not on/off keyed - quite intentionally - and FSK Hell needs more setting up than RTTY. Next time a request like that arrives, I'll be boring and just give them an I/Q upconverter + linear amp. Which reminds me - where is all that datmode software that delivers I/Q stereo outputs. Its only another line or two of code surely. Andy www.g4jnt.com
[digitalradio] Re: Direct RTTY Generation
OK Tnx... found the COM port output facility and got it working on a Desktop with a proper COM1. But when I tried a USB COM port - as suspected it wouldn't work directly. On trying the EXTFSK option, it just comes back with a message that says Can't Configure EXTFSK Downloaded the latest MMTTY version 1.66G, just to make sure. What I'm not sure about, if EXTFSK is set as the data output option, how does the software know which USB Comport is to be used for its output of the data - if that makes sense :-) One FTDI USB COM port appears as COM 2 on this machine, another one as COM5 and a third one as COM 15. (I do have several more as well, all made from FT232 chips. Use the interface for everything)So how can it identify which of these is the one to use for EXTFSK ?? Andy www.g4jnt.com(author of the 'Data' and 'Design Notes' Columns in 'RadCom') MMTTY provides this FSK signal via the TxD pin of the serial port specified in the PTT FSK panel on the Setup MMTTY window's TX tab. Since using this signal requires a serial port capable of 45 baud operation, which some USB-to-serial-port-adaptors can't do, you can set the PTT FSK panel's port selector to EXTFSK, which displays a window that lets you configure the generation of an FSK signal on a serial port's RTS or DTR pins. In this latter configuration, the timing of the FSK signal is software-generated, and thus less accurate than that generated by a 45 baud serial port. Digital mode applications that use MMTTY as their RTTY Engine -- WinWarbler, HamScope, etc. -- thus offer this capability. While I realise there may be little call for such a one-wire drive now Not true! Modern transceivers provide RX filtering for RTTY that is only availalble when the transceiver is operated in RTTY mode, thus requiring the FSK signal when transmitting. Icom's ic-7200, ic-7600, ic-7700, and ic-7800 all provide a very nice twin-peak filter that is only available in RTTY mode. 73, Dave, AA6YQ
[digitalradio] Re: Direct RTTY Generation
A simple QRP Tx suitable for beginners, for example, is usually the ubiquitous 1 Watt 40m thing for CW that all the magazines and book seem include ad-ad-naueam, built into sweet tins or whatever novel box they can think of. I want to be different, and publish a design for RTTY. A simple varicap across a crystal, needing a bit of applied science with SSB Rx and Spectrogram prog to set the shift - all part of the basic learning process. But to do that needs a way of driving the Tx with a wire that just waggles 1/0 with RTTY data - just like the mechanical teleprinters of old. So long as it does it at 45 or 50 baud and is properly timed (perhaps not so easy using Windoze - could this be why there's nothing out there?) I wanted to steer away from a design that linearly upconverted from a soundcard then filtered and amplified the result.The request was for simple designs for beginners Andy --- In digitalradio@yahoogroups.com, Simon HB9DRV simon.br...@... wrote: Andy, Can you be more specific about the design requirements? Simon Brown, HB9DRV http://sdr-radio.com From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On Behalf Of AC TALBOT
[digitalradio] Re: directly modulate computer /thus eliminating transceiver audio input
If only more software authours would provide their audio drive in stereo I/Q form it would make direct upconversion a real doddle. If the signals were generated at baseband, even poor I/Q balance would not be too serious, as the image then lies on top of the wanted signal. For narrow band modes, say no more than a couple of hundred Hz wide, a simple two opamp allpass network can be used to generate quadrature signals. 40dB isolation can be managed without too much effort. http://www.g4jnt.com/IQConverters.htm This is the soluition I use for generating linear 137 and 500kHz RF. http://www.g4jnt.com/LFUpconv.pdf Andy G4JNT --- In digitalradio@yahoogroups.com, obrienaj k3uka...@... wrote: I am developing a 'modem' to directly modulate computer generated modes to RF thus eliminating the requirement of using a transceiver audio input Welcome to the group, tell us more. Andy K3UK
[digitalradio] Re: NUE PSK31 Modem
Tnx... That link didn't work when I originally posted the message. Must have been a temprary glitch. I was really hoping for just the constructional details and firmware rather than a black box kit. Still... Andy www.g4jnt.com --- In digitalradio@yahoogroups.com, Siegfried Jackstien siegfried.jackst...@... wrote: http://www.nue-psk.com/ dg9bfc sigi
[digitalradio] Re: Coming May 1st: Get ready for Gridloc Hell!
My thoughts too. Pity about those in E Sussex and Kent - completely worthless. Andy www.g4jnt.com IO90IV58EI (GBR36) or IO90IV58AH (WGS84) --- In digitalradio@yahoogroups.com, Neil g7aqk...@... wrote: Not much point in contacting me then! G7AQK JO01ai --- In digitalradio@yahoogroups.com, scollaysquarewriter WB2HTO@ wrote: It's a brand new Award from the Feld Hell Club and it starts in about a week.
[digitalradio] ROS discussion - will it ever end
rgh I don't hink I can stand it any more and will just have to unsubscribe from this group.I originally joined it as being the author of the Data column in RSGB's RadCom, felt I ought to keep in touch with the people who actually use the datamodes and was hoping for a decent set of technical-type postings on the way datamode usage was moving amongst amateurs. But close to 1000 postings on the legality or otherwise of using a bog-standard SSB bandwidth single tone hopped frequency diversity system is just too much. If your FCC is anything like Ofcom, they'd just rather amateurs got on with their life and bothered them as slittle as possible, at least until a real issue arises. Its not as if you have the death penalty over there. (Actually, yes you do don't you, but presumably not for exceeding the regulated bandwidth on the amateur bands) It is far, far easier to beg forgiveness that it is to ask Permission - Solon - the lawmaker of Athens, 437 BCE Andy www.g4jnt.com
