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Measuring filter shape factor
At the time I did my test, I had a "hole" in my generators. The audio
gear went as high as 100k, and the RF gear went as low at 1Mhz, but the IF was 455Khz. Hence I tested the whole audio path. The impedances in the radio itself will effect the performance of the filter, so there is something to be said for in-situ measurements. Oh yeah, note that Abramoff didn't donate any money to the Democrats. rkhalona wrote: Michael Thorpe wrote: Amongst all these political propaganda posts, I wonder if there is a little room for a technical question related to radio please? If so, here goes: How does one measure the IF filter shape factor in a shortwave radio? I am technically minded and do have a signal generator, etc., but I am not sure of the exact procedure. Do I get the audio level at the peak frequency, then detune both sides off the peak for -3dB of the demodulated audio, note down the width between these points, then detune to obtain for -50dB of the demodulated audio, get the width at these points, and then the ratio of the two widths is the filter shape factor? I would appreciate a link to the exact procedure if there is one (don't seem to be able to find this in Google) or an expert advice please. I would also appreciate advice as to what actual values of filter shape are considered poor, good, excellent, etc... Thanks in advance, Michael You need to generate a swept frequency response of the IF filter Take a look at the following article on filter selectivity: http://www.radio-electronics.com/inf...electivity.php The shape factor is traditionally defined as BW(-60dB) SF =--------------- BW(-6dB) (see the third figure in the article illustrating a typical filter response and the meaning of the two bandwidths) For an ideal filter (see second figure), this bandwidth ratio would be equal to ONE (1.0). The closer the shape factor is to 1.0, the sharper the selectivity. For example, if you look at the specs for the Eton E1 on the following link (Monitoring Times review) http://www.monitoringtimes.com/html/...k-etone1xm.pdf the shape factor for the 7 KHz filter would be: SF = 12 KHz/7 KHz = 1.71 (not a very sharp filter, but not bad for a radio of this type) The other two filters have even worse shape factors. With DSP receivers, these filters can be made extremely tight and shape factors can be very close to 1.0. Hope this is helpful. Perhaps Pete can chime in with a detailed measurement procedure. RK |
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Measuring filter shape factor
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#3
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Measuring filter shape factor
I'm a National Review subscriber. Really. However, I don't read the
on-line version as it is routinely disinformation, i.e. articles that don't make it to the magazine. If you subscribe to the magazine, they will print retractions of what appears online. I will say at NR is the only conservative mag worth reading. They never stooped to the level of say the Spectator. David wrote: On 11 Jan 2006 17:23:37 -0800, wrote: At the time I did my test, I had a "hole" in my generators. The audio gear went as high as 100k, and the RF gear went as low at 1Mhz, but the IF was 455Khz. Hence I tested the whole audio path. The impedances in the radio itself will effect the performance of the filter, so there is something to be said for in-situ measurements. Oh yeah, note that Abramoff didn't donate any money to the Democrats. Read Rich Lowrie's latest editorial at National Review Online. |
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Measuring filter shape factor
David wrote:
On 11 Jan 2006 21:06:53 -0800, wrote: Read Rich Lowrie's latest editorial at National Review Online. He says the Abramoff scandal is 100% Republicans. Then he's stupid, or ignorant, or lying. 40 out of 45 Senate Democrats got money from Abramoff. Senator John Kerry (D-MA) received at least $98,550 in Abramoff-linked cash. Senator Harry Reid (D-NV) received at least $68,941 in Abramoff-linked cash. Senator Tom Harkin (D-IA) received at least $45,750 in Abramoff-linked cash. Senator Hillary Clinton (D-NY) received at least $12,950 in Abramoff-linked cash. Senator Patty Murray (D-WA) received at least $78,991 in Abramoff-linked cash. Senator Chuck Schumer (D-NY) received at least $29,550 in Abramoff-linked cash. Senator Debbie Stabenow (D-MI) received at least $6,250 in Abramoff-linked cash. Senator Max Baucus (D-MT) received at least $22,500 in Abramoff-linked cash. Senator Evan Bayh (D-IN) received at least $6,500 in Abramoff-linked cash. Senator Joseph Biden (D-DE) received at least $1,250 in Abramoff-linked cash. Senator Jeff Bingaman (D-NM) received at least $2,000 in Abramoff-linked cash. Senator Barbara Boxer (D-CA) received at least $20,250 in Abramoff-linked cash. Senator Maria Cantwell (D-WA) received at least $21,765 in Abramoff-linked cash. Senator Tom Carper (D-DE) received at least $7,500 in Abramoff-linked cash. Senator Kent Conrad (D-ND) received at least $8,000 in Abramoff-linked cash. Senator Jon Corzine (D-NJ) received at least $7,500 in Abramoff-linked cash. Senator Chris Dodd (D-CT) received at least $14,792 in Abramoff-linked cash. Senator Byron Dorgan (D-ND) received at least $79,300 in Abramoff-linked cash. Senator Dick Durbin (D-IL) received at least $14,000 in Abramoff-linked cash. Senator Dianne Feinstein (D-CA) received at least $2,000 in Abramoff-linked cash. Senator Russ Feingold (D-WI) received at least $1,250 in Abramoff-linked cash. Senator Daniel Inouye (D-HI) received at least $9,000 in Abramoff-linked cash. Senator Jim Jeffords (I-VT) received at least $2,000 in Abramoff-linked cash. Senator Tim Johnson (D-SD) received at least $14,250 in Abramoff-linked cash. Senator Ted Kennedy (D-MA) received at least $3,300 in Abramoff-linked cash. Senator Mary Landrieu (D-LA) received at least $28,000 in Abramoff-linked cash. Senator Pat Leahy (D-VT) received at least $4,000 in Abramoff-linked cash. Senator Carl Levin (D-MI) received at least $6,000 in Abramoff-linked cash. Senator Joe Lieberman (D-CT) received at least $29,830 in Abramoff-linked cash. Senator Blanche Lincoln (D-AR) Received At Least $14,891 in Abramoff-linked cash. Senator Barbara Mikulski (D-MD) received at least $10,550 in Abramoff-linked cash. Senator Bill Nelson (D-FL) received at least $20,168 in Abramoff-linked cash. Senator Ben Nelson (D-NE) Received At Least $5,200 in Abramoff-linked cash. Senator Barack Obama (D-IL) received at least $7,500 in Abramoff-linked cash. Senator Mark Pryor (D-AR) received at least $2,300 in Abramoff-linked cash. Senator Jack Reed (D-RI) received at least $3,500 in Abramoff-linked cash. Senator John Rockefeller (D-WV) received at least $4,000 in Abramoff-linked cash. Senator Ken Salazar (D-CO) received at least $4,500 in Abramoff-linked cash. Senator Paul Sarbanes (D-MD) received at least $4,300 in Abramoff-linked cash. Senator Ron Wyden (D-OR) received at least $6,250 in Abramoff-linked cash. -- If John McCain gets the 2008 Republican Presidential nomination, my vote for President will be a write-in for Jiang Zemin. |
#6
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Measuring filter shape factor
There is a difference between getting money from tribes, and getting
money from Abramoff. You should switch from kool-aid to beer. clifto wrote: David wrote: On 11 Jan 2006 21:06:53 -0800, wrote: Read Rich Lowrie's latest editorial at National Review Online. He says the Abramoff scandal is 100% Republicans. Then he's stupid, or ignorant, or lying. 40 out of 45 Senate Democrats got money from Abramoff. Senator John Kerry (D-MA) received at least $98,550 in Abramoff-linked cash. Senator Harry Reid (D-NV) received at least $68,941 in Abramoff-linked cash. Senator Tom Harkin (D-IA) received at least $45,750 in Abramoff-linked cash. Senator Hillary Clinton (D-NY) received at least $12,950 in Abramoff-linked cash. Senator Patty Murray (D-WA) received at least $78,991 in Abramoff-linked cash. Senator Chuck Schumer (D-NY) received at least $29,550 in Abramoff-linked cash. Senator Debbie Stabenow (D-MI) received at least $6,250 in Abramoff-linked cash. Senator Max Baucus (D-MT) received at least $22,500 in Abramoff-linked cash. Senator Evan Bayh (D-IN) received at least $6,500 in Abramoff-linked cash. Senator Joseph Biden (D-DE) received at least $1,250 in Abramoff-linked cash. Senator Jeff Bingaman (D-NM) received at least $2,000 in Abramoff-linked cash. Senator Barbara Boxer (D-CA) received at least $20,250 in Abramoff-linked cash. Senator Maria Cantwell (D-WA) received at least $21,765 in Abramoff-linked cash. Senator Tom Carper (D-DE) received at least $7,500 in Abramoff-linked cash. Senator Kent Conrad (D-ND) received at least $8,000 in Abramoff-linked cash. Senator Jon Corzine (D-NJ) received at least $7,500 in Abramoff-linked cash. Senator Chris Dodd (D-CT) received at least $14,792 in Abramoff-linked cash. Senator Byron Dorgan (D-ND) received at least $79,300 in Abramoff-linked cash. Senator Dick Durbin (D-IL) received at least $14,000 in Abramoff-linked cash. Senator Dianne Feinstein (D-CA) received at least $2,000 in Abramoff-linked cash. Senator Russ Feingold (D-WI) received at least $1,250 in Abramoff-linked cash. Senator Daniel Inouye (D-HI) received at least $9,000 in Abramoff-linked cash. Senator Jim Jeffords (I-VT) received at least $2,000 in Abramoff-linked cash. Senator Tim Johnson (D-SD) received at least $14,250 in Abramoff-linked cash. Senator Ted Kennedy (D-MA) received at least $3,300 in Abramoff-linked cash. Senator Mary Landrieu (D-LA) received at least $28,000 in Abramoff-linked cash. Senator Pat Leahy (D-VT) received at least $4,000 in Abramoff-linked cash. Senator Carl Levin (D-MI) received at least $6,000 in Abramoff-linked cash. Senator Joe Lieberman (D-CT) received at least $29,830 in Abramoff-linked cash. Senator Blanche Lincoln (D-AR) Received At Least $14,891 in Abramoff-linked cash. Senator Barbara Mikulski (D-MD) received at least $10,550 in Abramoff-linked cash. Senator Bill Nelson (D-FL) received at least $20,168 in Abramoff-linked cash. Senator Ben Nelson (D-NE) Received At Least $5,200 in Abramoff-linked cash. Senator Barack Obama (D-IL) received at least $7,500 in Abramoff-linked cash. Senator Mark Pryor (D-AR) received at least $2,300 in Abramoff-linked cash. Senator Jack Reed (D-RI) received at least $3,500 in Abramoff-linked cash. Senator John Rockefeller (D-WV) received at least $4,000 in Abramoff-linked cash. Senator Ken Salazar (D-CO) received at least $4,500 in Abramoff-linked cash. Senator Paul Sarbanes (D-MD) received at least $4,300 in Abramoff-linked cash. Senator Ron Wyden (D-OR) received at least $6,250 in Abramoff-linked cash. -- If John McCain gets the 2008 Republican Presidential nomination, my vote for President will be a write-in for Jiang Zemin. |
#7
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[OT] Measuring filter shape factor
wrote:
clifto wrote: David wrote: On 11 Jan 2006 21:06:53 -0800, wrote: Read Rich Lowrie's latest editorial at National Review Online. He says the Abramoff scandal is 100% Republicans. Then he's stupid, or ignorant, or lying. 40 out of 45 Senate Democrats got money from Abramoff. There is a difference between getting money from tribes, and getting money from Abramoff. You should switch from kool-aid to beer. It took me all of 120 seconds to find this in the liberal Chicago Tribune: http://www.chicagotribune.com/news/local/southsouthwest/chi-0601110210jan11,1,5780990.story?coll=chi-newslocalssouthwest-hed "Kennedy on Tuesday also explained why Weller used $1,640 of his own money to reimburse a lobbying firm where Abramoff once worked for a 1999 trip to two Indian reservations in Louisiana and Mississippi. "He visited those reservations at the request of former U.S. Rep. David Funderburk (R-N.C.), and THOUGHT THE TRIBES HAD PAID FOR THE TRIP [emphasis by clifto], Kennedy said. As soon as he confirmed otherwise, he repaid the money from his own pocket, he said." Here's one from liberal rag UnionLeader.com: http://www.theunionleader.com/article.aspx?headline=Sullivan+defends+Democrats+k eeping+lobbyist%E2%80%99s+money&articleId=c0963d8c-692b-47e6-b316-f42c8053aeef "Top Democrats received donations from scandal-plagued Washington lobbyist Jack Abramoff?s Indian tribe clients for legitimate reasons and are right to refuse to give up the money, the state?s Democratic chairman says." I bet if I took the time to search further, which I'm not going to bother doing, I could find *tribal* money going to Democrats via Abramoff in mass quantities. Note that unlike most of the Republicans involved, Kennedy and Reid have no intention of giving the money back or giving it to charity. They're keeping it. -- If John McCain gets the 2008 Republican Presidential nomination, my vote for President will be a write-in for Jiang Zemin. |
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Measuring filter shape factor
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