[digitalradio] Re: Time to start a PSK qrp freq?
A good concept. Looking though the web searches, there's some feedback to that point. However, where you suggest would put you up with some other offenders, particularly RTTY. I don't think it matters where you go, you'll still get stomped on if your QRP. If folks would just lower their power when the contact is close (like watching a OR to CA QSO wiping my waterfall out), just slide the soundcard volume level down (thus reducing your power output) and all is good. But, in my experience, most digimode QSOs are short, and seldom interfere for long. Unless it's a contest or that nut W0EAT calling for PSK aliens again. f
[digitalradio] Re: Time to start a PSK qrp freq?
--- In digitalradio@yahoogroups.com, Simon \(HB9DRV\) simon.br...@... wrote: If someone is suffering from strong signals I would want to know what radio and soundcard he's using, also a screenshot of the waterfall can help. Simon, is this a good example? http://forums.ham-radio.ch/attachment.php?attachmentid=4202d=1241122251 That particular station was about 1700 miles from me. I get them often enough, so can provide other samples if it helps. Thank you for the screenshots, it was nice to see a comparison. More an issue for me is losing the other stations from the over-driven signal of a strong one. I have a noise canceling signal enhancer now, but it's proving to require more experience and a good sensing antenna. Using a Kenwood TS-450S and a Sound Blaster Live PCI card. SignaLink interface (no USB, thus no soundcard in it.) f
Re: [digitalradio] Re: Time to start a PSK qrp freq?
Being as fair as I can I suggest that this is not an over-driven signal, he's just strong. DM780 5.0's enhancement option will really help as would a 500Hz filter in the 450 if possible. If you're thinking about a new radio look at the TS-480SAT - IMO the best digital-mode radio. Simon Brown, HB9DRV www.ham-radio-deluxe.com - Original Message - From: frankk2ncc frank.k2...@gmail.com That particular station was about 1700 miles from me. I get them often enough, so can provide other samples if it helps. Thank you for the screenshots, it was nice to see a comparison. More an issue for me is losing the other stations from the over-driven signal of a strong one.
[digitalradio] Re: Time to start a PSK qrp freq?
--- In digitalradio@yahoogroups.com, Simon \(HB9DRV\) simon.br...@... wrote: Being as fair as I can I suggest that this is not an over-driven signal... Yeah, I figure most signals I see, particularly PSK, aren't over driven, as the trace looks clean, but my rig's notch capability isn't what I'd like. The 500Hz filter is a good idea (about 150 bucks new), and this rig allows any filter combination, regardless of mode, so would be a sweet addition. The 480SAT is certainly a fine rig, as Rob, AA6A would attest, but another rig is about 1000$ behind getting a better antenna. There always seems to be something more important than my hobby to pay. DM780 5.0's enhancement option will really help... I look forward to trying it, thank you! f
Re: [digitalradio] Re: Time to start a PSK qrp freq?
Hi, Keep an eye out for a second-hand 480SAT - I've heard of them going for ~ $500. Simon Brown, HB9DRV www.ham-radio-deluxe.com - Original Message - From: frankk2ncc frank.k2...@gmail.com The 480SAT is certainly a fine rig, as Rob, AA6A would attest, but another rig is about 1000$ behind getting a better antenna. There always seems to be something more important than my hobby to pay.
Re: [digitalradio] Re: Time to start a PSK qrp freq?
I also find that using a combination of narrow filters and passband tuning helps dig out the weak ones in the presence of strong stations. I've been using an IC-7200 for the past few months. It's Twin Passband Tuning feature of the DSP lets you electronically narrow the IF passband. Very useful once you get the hang of using it. In general I don't see the problem with trying to establish a QRP Watering Hole for PSK31 but I think it might be better to stick with a base frequency such as 14.070 MHz but maybe encourage people to stick to QRP levels in a certain audio frequency range. When the propagation is good 30 meters is a great QRP band too. At least here in the US you avoid having to compete with the really high power stations. 73, Tim, N9PUZ kh6ty wrote: Frank, often the loss of a weak signal in the presence of a strong one is due to AGC capture by the strong station, which reduces the gain you need for the weak one. Try using passband tuning or IF shift to reduce the presence of the strong station in the passband so the AGC will not be affected by it so much. If you see the waterfall suddenly grow more dim when a strong station comes one, then you can suspect that the strong station has caused the AGC to reduce gain. On our PSK-20 QRP design (Smallwonderlabs.com), we do not use any AGC but have a wide dynamic range detector and there is never any loss of a weak signal when a strong one comes on, even right adjacent to the weak signal. I wish the transceiver manufacturers would start designing receivers that can dispense with AGC on digital modes without overloading the IF chain. 73, Skip KH6TY
Re: [digitalradio] Re: Time to start a PSK qrp freq?
Hi, Quite simple: I'll explain offline to yourself and Dave W1HKJ very soon. Simon Brown, HB9DRV www.ham-radio-deluxe.com - Original Message - From: Vojtech Bubnik bubn...@seznam.cz Hi Simon. The enhancement looks very interesting. How do you do that? BTW, I was trying to achieve nice CW waterfall like in Rocky, but I did not succeed. Your method looks promissing. 73, Vojtech
Re: [digitalradio] Re: Time to start a PSK qrp freq?
Skip makes a good point. Passband tuning and IF shift are effective in dealing with AGC capture. In some cases I have added attenuation in to the receiver as an additional measure to reduce front-end overload. philw de ka1gmn On Tue, Jun 16, 2009 at 9:27 AM, kh6ty kh...@comcast.net wrote: Frank, often the loss of a weak signal in the presence of a strong one is due to AGC capture by the strong station, which reduces the gain you need for the weak one. Try using passband tuning or IF shift to reduce the presence of the strong station in the passband so the AGC will not be affected by it so much. If you see the waterfall suddenly grow more dim when a strong station comes one, then you can suspect that the strong station has caused the AGC to reduce gain. On our PSK-20 QRP design (Smallwonderlabs.com), we do not use any AGC but have a wide dynamic range detector and there is never any loss of a weak signal when a strong one comes on, even right adjacent to the weak signal. I wish the transceiver manufacturers would start designing receivers that can dispense with AGC on digital modes without overloading the IF chain. 73, Skip KH6TY frankk2ncc wrote: More an issue for me is losing the other stations from the over-driven signal of a strong one. I have a noise canceling signal enhancer now, but it's proving to require more experience and a good sensing antenna. Using a Kenwood TS-450S and a Sound Blaster Live PCI card. SignaLink interface (no USB, thus no soundcard in it.) f
Re: [digitalradio] Re: Time to start a PSK qrp freq?
No AGC means all stages in the chain (including the first mixer) have to cope with a dynamic range of 130 dB (in a proper receiver). The only remedy is proper filtering as early in the chain as possible, with a carefully designed AGC system.. Some 25 years ago Ulrich Rohde has writtien some interesting articles about how to design a receiver, which are still valid. 73, Rein PA0R -Ursprüngliche Nachricht- Von: kh6ty kh...@comcast.net Gesendet: 16.06.09 16:28:57 An: digitalradio@yahoogroups.com Betreff: Re: [digitalradio] Re: Time to start a PSK qrp freq? Frank, often the loss of a weak signal in the presence of a strong one is due to AGC capture by the strong station, which reduces the gain you need for the weak one. Try using passband tuning or IF shift to reduce the presence of the strong station in the passband so the AGC will not be affected by it so much. If you see the waterfall suddenly grow more dim when a strong station comes one, then you can suspect that the strong station has caused the AGC to reduce gain. On our PSK-20 QRP design (Smallwonderlabs.com), we do not use any AGC but have a wide dynamic range detector and there is never any loss of a weak signal when a strong one comes on, even right adjacent to the weak signal. I wish the transceiver manufacturers would start designing receivers that can dispense with AGC on digital modes without overloading the IF chain. 73, Skip KH6TY frankk2ncc wrote: More an issue for me is losing the other stations from the over-driven signal of a strong one. I have a noise canceling signal enhancer now, but it's proving to require more experience and a good sensing antenna. Using a Kenwood TS-450S and a Sound Blaster Live PCI card. SignaLink interface (no USB, thus no soundcard in it.) f Announce your digital presence via our Interactive Sked Pages at http://www.obriensweb.com/sked Recommended digital mode software: Winwarbler, FLDIGI, DM780, or Multipsk Logging Software: DXKeeper or Ham Radio Deluxe. Yahoo! Groups Links -- http://pa0r.blogspirit.com Announce your digital presence via our Interactive Sked Pages at http://www.obriensweb.com/sked Recommended digital mode software: Winwarbler, FLDIGI, DM780, or Multipsk Logging Software: DXKeeper or Ham Radio Deluxe. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:digitalradio-dig...@yahoogroups.com mailto:digitalradio-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: digitalradio-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
