Hi All, To control a RF transmitter, I have to set its synthesizer paramter N: N = (fTX + foffset) / Xclk we know foffset and Xclk, it is easy to get N when I set any fTX. but the problem is, there is a register called: Local oscillator frequency extension. It has 2 bits for different range frequency. Why do I need this? If chip already know my target frequency, why should I tell him another information... the point is, I still don't know what is this register for .. For synthesizer, I have N... so what is that for .... Best regards, Boki.
RF Transmitter register setting.
Started by ●March 14, 2006
Reply by ●March 14, 20062006-03-14
<bokiteam@ms21.hinet.net> wrote in message news:1142329699.345206.56620@i39g2000cwa.googlegroups.com...> Hi All, > > To control a RF transmitter, I have to set its synthesizer paramter N: > > N = (fTX + foffset) / Xclk > > > we know foffset and Xclk, it is easy to get N when I set any fTX. > > but the problem is, there is a register called: > > Local oscillator frequency extension. > > It has 2 bits for different range frequency. > > Why do I need this?Don't you think that would be in the datasheet of the transmitter? Meindert
Reply by ●March 14, 20062006-03-14
No, no description for that... ><!!! I hope any expert can advice. Thanks! BR /Boki. Meindert Sprang wrote:> <bokiteam@ms21.hinet.net> wrote in message > news:1142329699.345206.56620@i39g2000cwa.googlegroups.com... > > Hi All, > > > > To control a RF transmitter, I have to set its synthesizer paramter N: > > > > N = (fTX + foffset) / Xclk > > > > > > we know foffset and Xclk, it is easy to get N when I set any fTX. > > > > but the problem is, there is a register called: > > > > Local oscillator frequency extension. > > > > It has 2 bits for different range frequency. > > > > Why do I need this? > > Don't you think that would be in the datasheet of the transmitter? > > Meindert
Reply by ●March 14, 20062006-03-14
bokiteam@ms21.hinet.net wrote:> Hi All, > > To control a RF transmitter, I have to set its synthesizer paramter N: > > N = (fTX + foffset) / Xclk > > > we know foffset and Xclk, it is easy to get N when I set any fTX. > > but the problem is, there is a register called: > > Local oscillator frequency extension. > > It has 2 bits for different range frequency. > > Why do I need this? > > If chip already know my target frequency, why should I tell him another > information... > > the point is, I still don't know what is this register for .. > > For synthesizer, I have N... so what is that for ....General background: synthesizers used for transceive operation (both receive and transmit) have to change frequency when going from transmit to receive. The amount of change is the IF frequency. LO +/- IF = actual signal you receive. I'm guessing the synthesizer used in your transmitter allows for receive operation too, possibly irrelevant to your application. (And since when is Boki known to every listen anyway?) How you use it... it'd help if you told us part numbers! Barring that, hook up a frequency counter, try all 4 bit combinations, and see what happens. I'm guessing that one of the two bits enables the shift, and the other selects the direction of the shift. The IF frequency may very well be fixed (and depends on the application... at low VHF it's probably 10.7MHz but it's possible an entirely different register programs this.) Tim.
Reply by ●March 14, 20062006-03-14
<bokiteam@ms21.hinet.net> wrote in message news:1142331562.507360.232080@v46g2000cwv.googlegroups.com...> No, no description for that... ><!!!Bad product then.> I hope any expert can advice.How can we, if you don't provide part numbers.... I don't have any crystal ball available! Meindert
Reply by ●March 14, 20062006-03-14
Meindert Sprang wrote:> <bokiteam@ms21.hinet.net> wrote in message > news:1142331562.507360.232080@v46g2000cwv.googlegroups.com... > > No, no description for that... ><!!! > > Bad product then. > > > I hope any expert can advice. > > How can we, if you don't provide part numbers.... > I don't have any crystal ball available!Sometimes I suspect that Boki is part of some highly-compartmentalized R&D operation. Think of it like a spy cell. He's probably not allowed to know the part numbers, and indeed many of the Chinese parts apparently have no data sheets that you or I would be allowed to look at (even though they're made by the billions). Heck, a lot of parts designed and made here in the West over the past couple of decades have useless data sheets too :-). Tim.
Reply by ●March 14, 20062006-03-14
You will think it again when you encounter that. Provide part number? I wish I can. BR /Boki. Meindert Sprang wrote:> <bokiteam@ms21.hinet.net> wrote in message > news:1142331562.507360.232080@v46g2000cwv.googlegroups.com... > > No, no description for that... ><!!! > > Bad product then. > > > I hope any expert can advice. > > How can we, if you don't provide part numbers.... > I don't have any crystal ball available! > > Meindert
Reply by ●March 14, 20062006-03-14
Can I use oscilloscope to measure the antenna directly ? ( it was on board on PCB) Tim Shoppa wrote:> bokiteam@ms21.hinet.net wrote: > > Hi All, > > > > To control a RF transmitter, I have to set its synthesizer paramter N: > > > > N = (fTX + foffset) / Xclk > > > > > > we know foffset and Xclk, it is easy to get N when I set any fTX. > > > > but the problem is, there is a register called: > > > > Local oscillator frequency extension. > > > > It has 2 bits for different range frequency. > > > > Why do I need this? > > > > If chip already know my target frequency, why should I tell him another > > information... > > > > the point is, I still don't know what is this register for .. > > > > For synthesizer, I have N... so what is that for .... > > General background: synthesizers used for transceive operation (both > receive and transmit) have to change frequency when going from transmit > to receive. The amount of change is the IF frequency. LO +/- IF = > actual signal you receive. > > I'm guessing the synthesizer used in your transmitter allows for > receive operation too, possibly irrelevant to your application. (And > since when is Boki known to every listen anyway?) > > How you use it... it'd help if you told us part numbers! Barring that, > hook up a frequency counter, try all 4 bit combinations, and see what > happens. I'm guessing that one of the two bits enables the shift, and > the other selects the direction of the shift. The IF frequency may very > well be fixed (and depends on the application... at low VHF it's > probably 10.7MHz but it's possible an entirely different register > programs this.) > > Tim.
Reply by ●March 14, 20062006-03-14
<bokiteam@ms21.hinet.net> a �crit dans le message de news:1142340969.033534.200990@i39g2000cwa.googlegroups.com...> Can I use oscilloscope to measure the antenna directly ? ( it was on > board on PCB) > >Yes, you can use a scope to measure your antenna. Just put the scope and the antenna side by side. When you got how much fraction of the scope length the antenna is, just check the scope length into its datasheet and multiply it by the fractional number. Voila, you've measured the antenna with the scope. -- Thanks, Fred.
Reply by ●March 14, 20062006-03-14
<bokiteam@ms21.hinet.net> wrote in message news:1142340716.391723.182360@i39g2000cwa.googlegroups.com...> You will think it again when you encounter that.Well, actually I never encounter that. When I design something, I always have datesheets of IC's/modules etc.etc. at hand. If not available, I simply do not use that part. What exactly are you designing? Is it business or hobby?> Provide part number? I wish I can.I don't get this. You are using an RF transmitter with some sort of interface. If you don't have a datasheet of that transmitter, how on earth are you going to use that thing. If you do have a datasheet, it is apparently incomplete, but you must have some sort of typenumber of the thing. Right? Meindert
