Posted: 11/13/2010 6:36:28 PM EDT
I have a Yeasu FT-450. It has the following IF-DSP functions:
I'm quite certain this is user error / inexperience. I've tried all of the functions in various combinations, but really only randomly trying to pull in weaker signals with very limited success. Contour and Notch seem to be the most heavily marketed functions, but I've had the least success getting any usable results from them. Is IF-DSP over-rated? I mostly operate (listen 90+%) on 75/80m at night. Daylight radio time is severely limited. What am I missing and/or doing wrong? How can I use these features to better effect them I'm getting? Thanks in advance for suggestions, -Slice |
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There are likely many different algorithms available for the noise reduction function. NR is the most useful function for DSP IMO.... if there are adjustments, give them a try.
If there's an auto notch filter those are handy on HF also, clobbers heterodynes and tuner-uppers almost transparently. |
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My rig doesn't have DSP, but I've found the most helpful to be the notch filter, then adjusting the RF gain and using the attenuator when appropriate. I sometimes adjust the shift, but extremely rarely. The noise block filter does absolutely nothing as far as I can tell. |
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Make sure you set your agc to fast. That helps the dsp to be able respond fast to static and crashes since your agc won't be rounding off the rise and fall times. Also use attenuation when noise level is high if your front-ends dynamic range is being swamped dsp isn't going to fix that.
Just some of my personal observations... |
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DSP isn't magic....it will never allow you to pull an unreadable signal out of the noise level. It will usually make a readable signal better and especially make it more enjoyable to listen to IMHO. I find the the IF shift, notch help the most with interference from an adjacent frequency, but as with all things....you get what you pay for and the FT-450 is not going to on the same level as some of the more expensive rigs. |
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Its been awhile since I last ran my 450 ... or any hf rig , like 8 months since any notable operation except to chat with a friend of mine on 80m ssb voice . I love PSK when I do feel like playing though . But IRC if you run it in CW mode it narrows the width filter a bit ... Ill check my manual . Okie according to the little info box on page 30 SSB width settings are 1.8 khz 2.4 khz 3.0 khz CW Mode are 500 hz 1.8 khz 2.4 khz Honestly all i ever use is the width and the IF shift , every blue moon I might hit the contour If this doesnt do it theres a 450 yahoo group that has a ton of info on this radio , I need to go over there and get acquainted with my radio . I like my little 450 even after running a 2000 kenwood ,756 icom and a 920 Yeasu if the 7200 would have been out that what I would have got but the 450 does what I want it to do and is simple enough I can relearn it again pretty quick when Im away from operating it for a while . If I had plenty of money the 450 would go in the camper permanently , I would get a 7200 for ecomm and a 950 for the base ..... but I dont talk enough on HF to justify all of that so the 450 will most likly be shared from camper to base and maybe in a year or so I can pick up a 7200 . |
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Quoted: I realize it's not the fanciest rig around. Can you help me understand how to use the notch (it's a manual notch on the FT-450) and IF Shift? I'm not suggesting it's worthless or magic, but rather that I don't know how to use it correctly... Play with it.....Read the manual....ask a friend to come over and show you how to use it. Watch the video. It shows how some of the functions work. http://www.youtube.com/watch?v=T6c7Dx5RzQU |
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My FT450 is my first experience with a DSP rig. And I have to say the IF DSP in this rig isn't quite the magic it is hyped to be Some combination of notch, shift, and width will get rid of just about any offending adjacent signal, and the contour will help boost a weak voice above the background noise, but the straight DNR doesn't cut a lot of QRN type noise without also adding a lot of distortion and muddiness to the desired signal.
Bottom line - it won't make an unreadable signal readable, but it does add some comfort with signals which are merely "difficult" to read, and the three bandpass shaping functions do what they are supposed to do fairly well.. |
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Quoted:
Can you help me understand how to use the notch (it's a manual notch on the FT-450) and IF Shift? The notch is great for eliminating an unwanted nearby heterodyne from a broadcast carrier, tuner-upper, etc. Some combination of width and IF shift is used to move and shape your passband to eliminate (especially) unwanted nearby SSB signals. You'll have to experiment with those controls as you encounter different forms of QRM, as every case is unique. Note the IF shift is most easily accessible - and on a crowded phone band also most useful. |
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Another really outstanding way to understand what the DSP is doing for you is to watch the audio output of your radio on an audio spectrum waterfall plot. You can use any ham digital mode software to do this for you. You don't even need a cable, just put the PC microphone near the radio speaker.
I use the width and notch features on my IC7000 all the time for digital. By using Ham Radio Deluxe radio control software I don't even have to remember all the crazy button presses to use those features as they appear as easy to understand sliders and buttons in HRD. I also use the DNR feature for voice. I rarely have used IF shift. On digital I will have it in full bandwidth, see a signal, auto-center it in the audio passband using that feature of DM780, pop a filter on that I've preset to an appropriate width for that mode (the IC7000 has three filter width memories) and then have at it. I'll bring the notches into play if the filter width is not quite optimal for some reason. |