From crl.com!frbspd Wed, 13 Apr 1994 16:07:47 PDT remote from crl Received: from crl by NetAcsys.com (UUPC/extended 1.12b) with UUCP; Wed, 13 Apr 1994 16:07:47 PDT Received: from crl.crl.com (crl.com) by nntp.crl.com with SMTP id AA18262 (5.65c/IDA-1.5 for ); Wed, 13 Apr 1994 13:45:46 -0700 Received: by crl.crl.com id AA16487 (5.65c/IDA-1.5 for mycal@NetAcsys.com); Wed, 13 Apr 1994 13:45:49 -0700 Date: Wed, 13 Apr 1994 13:45:49 -0700 From: Stephen Dunifer Message-Id: <199404132045.AA16487@crl.crl.com> To: mycal@netacsys.com (Mycal) Subject: Re: I'll be in Europe in May Newsgroups: alt.radio.pirate Organization: CRL Dialup Internet Access (415) 705-6060 [login: guest] X-Newsreader: TIN [version 1.2 PL2] In article <766263680.606snx@NetAcsys.com> you wrote: : I'll be in Europe in May, hanging out in Germany and taking many : trips around. I would like to visit some Euro-casters, and : I could possibly bring FRB and/or Ramsey kits for people. Mycal, Enclosed is the PLL information. I have a contact list for anarchist and other groups in Germany which I can send to you. There are a number of infoshops in Germany that would be really cool to visit. Let me know if you would like this list. I have some friends who could give some contacts as well. take care Stephen ----------------------- From DAVEFORBES@delphi.com Wed Apr 13 13:02:42 1994 Date: Sun, 10 Apr 1994 22:27:24 -0400 (EDT) From: DAVEFORBES@delphi.com To: frbspd@crl.com Subject: PLL stuff Steve, Here's the sedign notes and schematic of the loop filter that I made. Works from 50Hz up. The Problem An FM radio station wishes to frequency-modulate a 95.5-MHz carrier with a 5O Hz sine wave so that the peak frequency deviation is 75 kHz. That is, wi = 2pi(95.5MHz) = 600 Mrad/s (operating freq), wm = 2pi(50 Hz) = 314 rad/s (lowest audio freq), and delta wo = 2pi(75 kHz) cos wm t = (471 krad/s) cos wm t (maximum deviation). To get good programmability from a readily available reference frequency, we use a 20KHz loop frequency, and divide by N=4775. Using a large divide-by-N number worsens spurious modulation; we reduce this below with an extra low-pass filter element. To satisfy the FM modulator design rule K <= 2piBm1 where Bm1 is the low-freq. 3dB audio response: 50Hz with the highest K possible, let K = 314 rad/s. Calculating Loop Gain Our VCO has Ko = 6 Mrad/s/V (1 MHz/V). To determine the Ko of your VCO, hook it up to a pot and measure the voltage on the pot wiper and the frequency of the VCO, and calculate the ratio over the center half of the supply voltage. The voltage necessary to produce the modulation delta wo = 2pi(75 kHz) cos wm t is m(t) = delta wo/Ko = (80 mV) cos wm t. The MC145152's two-output phase detector uses CMOS outputs with VH = 5 V and VL = 0 V. So the maximum correction voltage out of the phase detector Vdm = VH Q VL = 5 V and the gain of the phase detector is Kd = Vdm/2piN = 5/(4775*2pi) = 160 uV/rad To realize the bandwidth K, we need a loop filter gain Kh = K/KdKo = 314/(160 u x 6 M) = 0.33 To minimize pullin time, we pick w2 as large as possible: w2 = K/4 = 78 rad/s. To reduce the spurious modulation, we place a pole at w3 = 4 K = 1256 rad/s by adding an additional passive low-pass filter to the input of the loop filter. The Loop Filter I used an active loop filter with two poles. These are w2 and w3, which set the response time and the spurious modulation as per above. The goal here is to barely pass the lowest bass notes by setting w2 to K/4, where K is the lowest nagular velocity we want to pass (the 3db low-end audio cutoff freq). The loop filter gain Kh we calculated above is set by the loop filter feedback ratio R2/R1: Kh = R2/R1 = 56K/164K = 0.34 where R1 is op-amp input resistor and R2 is feedback resistor. The active loop filter comprises a low-pass filter whose time constant is set by R2 and C: w2 = 1/(R2*C) = 1/(56K*.22uF) = 80 rad/s desired w2 = K/4 = 78 rad/s which is with 2%. where C is feedback cap. Next, we need to add another low-pass filter to the input of the op-amp set to w3. This reduces spurious modulation by reducing the loop- frequency component of the error signal fed back to the VCO. Do this by adding an RC filter to each leg of the op-amp inputs by splitting R1 into two resistors each R1/2 and letting w3 = 4/(R1*C3) = 4/(164K*.022uF) = 1108 rad/s desired w3 = 4 K = 1256 rad/s which is within 14%. where R1 is the sum of the input and output resistors of the input filter, and C3 is the capacitor to ground. Summary of component values for Ko=1MHz/volt VCO: R1/2 = 82K ohm R2 = 56K ohm C = 0.22 uF C3 = 0.022 uF Experimental conmfirmation gives -3dB response at 50Hz. VCO output spectrum is down 40dB at +/-500 Hz with unshielded VCO. From DAVEFORBES@delphi.com Wed Apr 13 13:03:01 1994 Date: Sun, 10 Apr 1994 22:29:28 -0400 (EDT) From: DAVEFORBES@delphi.com To: frbspd@crl.com Subject: PLL part 2 Programming the FS I used a div by 64/65 prescaler. This gives good range for future UHF work and makes it easy to calculate the programming of the FS. Using a 5.12 MHz crystal, set the RA2:0 bits to 011 to select /256 mode for a 20 KHz loop frequency. This makes the reference whine inaudible. Now the A bits and the N bits form a binary number which is the desired freq. over 20KHz. The form is NNNNNNNNNNAAAAAA. Just divide your freq. by 20 KHz and convert to binary. Add a jumper for a 0 and remove a jumper for a 1. Example: 105.1 MHz / 20 KHz = 5255. = 0x1487 Convert to binary: 0001 0100 1000 0111 Install jumpers for 0 bits: pin 2111 1111 1112 2222 0987 6543 2105 4213 bit NNNN NNNN NNAA AAAA 9876 5432 1054 3210 value 0001 0100 1000 0111 For FM band use only, the five bits N9:5 may be tied permanently to the value 00010. This allows coverage of the freq. range 81.92 to 122.86 MHz. The Circuit 0.22 R2 | | +--/\/\/\---| |-+ MC145152 | | | | | | | \ C | | 8 R1/2 R1/2 | 2 | \ | phi V|---/\/\/\-*------/\/\/\-*---|- \ 6 | | 7 82K | 82K 3 | LF356 >---*----O Vc phi R|---/\/\/\-+----*-/\/\/\-*---|+ / Kvco = | R1/2 | | R1/2 | | / -1MHz/Volt | | | | | / C Fpd=20KHz C3 --- --- C3 | | | --- --- +--/\/\/\---| |-+ |.022| R2 | | | | | 0.22 | ground> --- --- --- - - - I hope you like it. From DAVEFORBES@delphi.com Wed Apr 13 13:29:25 1994 Date: Tue, 12 Apr 1994 04:16:25 -0400 (EDT) From: DAVEFORBES@delphi.com To: frbspd@crl.com Subject: PLL circuit change Steve, I have discovered a problem with the circuit I sent yesterday. The VCO constant Ko is -1MHz/volt. It turns out that the ECG612 varactor I was using is packaged backwards form a Motorola MV2104, which part number I saw faintly under the ECG612 label. I used the Motorola data sheet, which caused me to forward-bias the varactor, getting a different (but functional) capacitance characteristic. To correct the circuit for a correctly-installed varactor, just swap pins 7 and 8 of the MC145152. I have also hooked up a BA1404 to get stereo modulation. It works well. In fact, the stereo carrier is cleaner than the one coming out of KUAT-FM, the local university classical station!! I can't wait to get this thing into production. It's real well-behaved. Gotta go now. --David -------------------------- TAKE BACK THE AIRWAVES - THE SPRING & SUMMER OFFENSIVE Free Radio Berkeley / Free Communications Coalition First, we would like to thank everyone for their support of micro power liberation broadcasting and their extreme degree of patience as we get our act together on ramping up for full scale production of kits. FRB and the Peoples' FCC invite you to take part in reclaiming the airwaves. This can be done in many ways, it is not necessary for you and your community to put a station on the air if you feel that is too great of a risk. A lot of public education needs to happen around this issue so folks understand that is a matter of free speech, constituitional and human rights. We urge you to consider conducting public forums and presentations on this in your community. Printed materials, videos, etc. can be provided for this type of activity. Further, if you are technically inclined and would like to provide assistance as a mentor to those whose technical abilities are vastly exceeded by their enthusiasm, we would like to hear from so we can refer folks needing assistance to someone in their area. If your are good at teaching and presenting technical matters in an understable manner, please consider leading a workhsop in your community. We can supply materials for this including a how to video that is in production. We need any information on what happening in your community as it regards micro power broadcasting, especially regarding any actions taken by the FCC. Micro power broadcasting will be part of the Lolapalooza tour this summer. A transmitter will accompying some foks who are part of the tour and we have been invited to have a table at each concert site. If you live anywhere close to the concert sites (most major urban areas) and can volunteer to run an info table, pleaes contact us. We will see that passes are arranged and send you the materials to be distributed along with materials you might wish to add. That would be a good time to organize a local meeting/public forum or workshop on micro power broadcasting and reclaiming the airwaves. All in all, the Lolapalooza tour was attended by 2 million people last year, a great opportunity for outreach. Let us know if there is any way we can help you, many of us here are rather experienced community activists and organizers. We have legal support available through the National Lawyers Guild and can send legal info to supportive attorneys in your area to bring them up to speed on this issue. If you can, come to the Bay Area for the weeekend of April 30 and May 1 and the following week. On Saturday, April 30 Food Not Bombs is putting on Soupstock 94 with lots of good bands including MDC, Mudwimmin, Clan Dyken, etc. It will be held at the Golden Gate Park Bandshell near the DeYoung Museum and starts at 12 noon. San Francisco Liberation Radio will be broadcasting it live at 93.7 FM with a possible higher power AM simulcast. On Sunday, May 1 the 25th anniversary of Peoples' Park will be celebrated with a big party and concert at Peoples' Park in Berkeley. This event will be broadcast live by Free Radio Berkeley at 88.1 FM. A whole series of workshops on media, computers, broadcasting, etc. will be held that week in both SF and Berkeley. A public forum on micro power broadcasting and radical art will be held on Thursday evening, May 5 at the Capp Street Gallery in SF. A micropower broadcasting workshop will held on Wednesday, May 4 in Berkeley and on Saturday, May 6 at the Capp Street Gallery in SF. More article are coming out on mirco power broadcasting. The most recent issue of Option had a very good article. The May issue of Spin will feature an article as well. It is possible that Rolling Stone might be interested in this issue. Hopefully, you can get the local media in your area to do the same. Richard Edmondson with San Francisco Liberation Radio and Food Not Bombs Radio Network is now producing a weekly show for Radio For Peace International, a shortwave station operating from Costa Rica. It is a half hour show on the best of micro power broadcasting in the US with segments from air tapes of various stations that are currently on the air. If you are on the air send us air tapes so they can be incorporated into the show. We are setting up to record program materials onto hard disk with a DSP card in one our PCs. These will be compressed with a program from Xing and loaded into our FTP site for distribution. This will begin on May 1. If you are interested in this project, let us know We have decided to make a major push for next 6 months to create a national movement to take back the airwaves and break the coporate/government stranglehold on the free flow and exchange of ideas, information, news, music, culture and artistic expression. If we do this in an organized, concerted way we can take back the airwaves and show what real democracy is all about. It involves taking risks and a lot of hard work but if worth the effort if one values free speech, human rights, liberty and self determination. Thanks again. Stephen Dunifer Doug Forbes Richard Edmondson Keith McHenry Captain Fred JS Universal Radio and many others who wish to remain unknown at this time Contact: Free Radio Berkeley / Free Communications Coalition 1442 A Walnut St. #406 Berkeley, CA 94709 (510) 464-3041 - voice mail email - frbspd@crl.com ftp site: crl.com - directory: /ftp/users/ro/frbspd Send us any program material you might have.