To Bobs comments your right. That 75 MHz may not be needed because of the 1575 input filter. That would save $29. By the way I was shocked to see for all of $3 complete 1575 filter and LNA chips. The only nasty challenge is the chips are extremely small. The cost is low enough I can purchase several in case I screw it up. Its clearly going to be at my maximum soldering skills. Regards Paul WB8TSL
On Wed, Dec 2, 2015 at 10:32 AM, paul swed <[email protected]> wrote: > My bad mixing threads here the 1575 filter is in mouser and digikey has > them. > The 75 MHz is straight from mini-circuits. > Regards > Paul > WB8TSL > > On Wed, Dec 2, 2015 at 10:31 AM, paul swed <[email protected]> wrote: > >> Sorry mouser electroncs. >> >> On Wed, Dec 2, 2015 at 8:10 AM, Herbert Poetzl <[email protected]> >> wrote: >> >>> On Tue, Dec 01, 2015 at 08:33:05PM -0500, paul swed wrote: >>> > Digikey was a strike out with 1 filter for 86 cents but >>> > order was 1000 units. >>> >>> Sorry, but could you point me to the filter in question >>> please, I couldn't find anything on digikey, but probably >>> I was searching for the wrong keywords. >>> >>> Thanks in advance, >>> Herbert >>> >>> > Mouser however has a wide assortment very reasonable and >>> > by the single units. >>> >>> > Hardest thing will be soldering them. >>> >>> > Regards >>> > Paul >>> > WB8TSL >>> > >>> > >>> > On Tue, Dec 1, 2015 at 8:29 PM, paul swed <[email protected]> wrote: >>> > >>> > > Hello to the group have indeed done the 1575 down to 35.42 to 75.42 >>> and >>> > > upconverter trick. >>> > > Thats what I used for 2-3 years now and thought it was time to move >>> beyond >>> > > that approach. Especially due to the earlier conversation on old >>> receivers >>> > > and that they should still work just fine if you do not care about >>> the date. >>> > > >>> > > I actually have 2 versions of the 35 to 75 converter. One using an >>> odetics >>> > > down converter and another using a starlink gps receiver. Both have >>> 35.42 >>> > > MHz IFs. Old stuff you can get a soldering iron into. >>> > > >>> > > No intention to put this on the tower and mini-circuits makes a good >>> BPF >>> > > for the 75 MHz IF. Since I will believe the actual antenna has a 1571 >>> > > filter in it I was thinking of skipping it down in the shack. >>> > > >>> > > Will see what digikey and mouser has in the way of filters and if >>> > > inexpensive may buy one. I keep thinking I may actually have one >>> also. >>> > > Thanks again everyone. >>> > > Paul >>> > > WB8TSL >>> > > >>> > > On Tue, Dec 1, 2015 at 7:53 PM, Alex Pummer <[email protected]> >>> wrote: >>> > > >>> > >> for 70MHz it does not hurt to match the cable to the filter at the >>> > >> antenna unit [down converter] end and also match the filter at the >>> > >> receiver upconverter end, the cable will pick up enough noise to >>> overdrive >>> > >> the 70 something receiver's input [ the "outside" field will drive >>> a >>> > >> current in the cable's shield, but not in the center conductor, that >>> > >> current causes noise voltage between the two end of the cable's >>> shield >>> > >> which will end up at the input of the receiver, therefore it need >>> to be >>> > >> filtered out before it hits the mixer......also the down >>> converter's LO's >>> > >> reference is sensitive to the noise which the cable will pick up [ >>> will >>> > >> cause phase noise ], therefore it needs to be filtered ..... >>> > >> That down up converter system is an interesting project but it is >>> not >>> > >> that simple as it looks >>> > >> 73 >>> > >> KJ6UHN >>> > >> Alex >>> > >> >>> > >> >>> > >> On 12/1/2015 2:57 PM, Bob Camp wrote: >>> > >> >>> > >>> Hi >>> > >>> >>> > >>> Here’s sort of a backwards look at it: >>> > >>> >>> > >>> Do you *need* an IF filter in the downconverter? By that I’m asking >>> > >>> about a >>> > >>> filter better than a simple LC tank. Did they put the filter in the >>> > >>> downconverter >>> > >>> or in the main box? I would think that putting a fancy filter up >>> by the >>> > >>> antenna >>> > >>> would have been a less likely thing to do than putting it down in >>> the >>> > >>> main box. >>> > >>> >>> > >>> Bob >>> > >>> >>> > >>> >>> > >>> On Dec 1, 2015, at 9:48 AM, paul swed <[email protected]> wrote: >>> > >>>> >>> > >>>> Thanks everyone. The Meinberg is nice and maybe available from >>> Ebay by >>> > >>>> Alex's link. But its 35.42 much as the Odetics down converter. I >>> am >>> > >>>> looking >>> > >>>> to create a 75.42 Mhz IF. >>> > >>>> Mini-circuits makes just the right parts. But had several IF >>> bandwidths >>> > >>>> available. >>> > >>>> So will go with the 2 or so MHz filter as suggested. >>> > >>>> >>> > >>>> I have the typical GPS better quality high gain antenna 1/2" >>> Heliax >>> > >>>> feed to >>> > >>>> a low noise gain block that makes up for the loss of a 8 X >>> splitter. >>> > >>>> I may add a 1575 filter ahead of the 10 db amplifier and then hit >>> the >>> > >>>> mixer. I think I have a filter. I actually question that I need >>> the >>> > >>>> filter >>> > >>>> or 10 db amp. May build without it to see what happens. Can >>> easily add >>> > >>>> it. >>> > >>>> The LO will be a mini-circuits dsn-2036 followed by a 10 db amp >>> to drive >>> > >>>> the mixer another mini-circuit DBM. The IF drives a bpf-a76+ and >>> then >>> > >>>> will >>> > >>>> follow that with 30 db of gain at 75 MHz. >>> > >>>> At least thats my thinking. >>> > >>>> Regards >>> > >>>> Paul >>> > >>>> WB8TSL >>> > >>>> >>> > >>>> On Tue, Dec 1, 2015 at 1:36 AM, Magnus Danielson < >>> > >>>> [email protected] >>> > >>>> >>> > >>>>> wrote: >>> > >>>>> Hi, >>> > >>>>> >>> > >>>>> This is a side-track to Pauls original question, but maybe a nice >>> > >>>>> little >>> > >>>>> point to make now that Peter touched on the subject. >>> > >>>>> >>> > >>>>> To elaborate a little on C/A and multipath surpression. >>> > >>>>> The multipath surpression of the receiver depends on code rate, >>> > >>>>> bandwidth >>> > >>>>> and correlator spacing. P-code is able to surpress more, and the >>> C/A >>> > >>>>> code >>> > >>>>> errors look about the same as the P-code, but scaled accordingly. >>> > >>>>> Increasing the bandwidth helps to reduce the C/A errors, but >>> taking the >>> > >>>>> next step of using narrow correlators further reduces the error. >>> This >>> > >>>>> is >>> > >>>>> shown already in the classical Spiliker book, but further >>> readings from >>> > >>>>> Novatel could be nice. >>> > >>>>> >>> > >>>>> Increasing the bandwidth and narrowing the early and late >>> correlator >>> > >>>>> taps >>> > >>>>> both have the effect of reducing the time over which energy goes >>> into >>> > >>>>> the >>> > >>>>> E-L difference, and hence reducing the impact of multipath into >>> the >>> > >>>>> solution. >>> > >>>>> >>> > >>>>> Cheers, >>> > >>>>> Magnus >>> > >>>>> >>> > >>>>> >>> > >>>>> On 12/01/2015 06:00 AM, Peter Monta wrote: >>> > >>>>> >>> > >>>>> What should the IF pass band bandwidth be? >>> > >>>>>>> >>> > >>>>>>> >>> > >>>>>>> For GPS C/A with wide correlator, about 2 MHz; if you want >>> Galileo >>> > >>>>>> BOC and >>> > >>>>>> (eventually) GPS L1C, or legacy C/A with narrow correlator, >>> about 8 >>> > >>>>>> MHz; >>> > >>>>>> for GPS P code about 20 MHz. Books on GNSS software receivers >>> will >>> > >>>>>> detail >>> > >>>>>> the many tradeoffs available---if you're starting out with a >>> > >>>>>> proof-of-concept lab receiver, go for 8 MHz. >>> > >>>>>> >>> > >>>>>> Cheers, >>> > >>>>>> Peter >>> > >>>>>> _______________________________________________ >>> > >>>>>> time-nuts mailing list -- [email protected] >>> > >>>>>> To unsubscribe, go to >>> > >>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> > >>>>>> and follow the instructions there. >>> > >>>>>> >>> > >>>>>> _______________________________________________ >>> > >>>>>> >>> > >>>>> time-nuts mailing list -- [email protected] >>> > >>>>> To unsubscribe, go to >>> > >>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> > >>>>> and follow the instructions there. >>> > >>>>> >>> > >>>>> _______________________________________________ >>> > >>>> time-nuts mailing list -- [email protected] >>> > >>>> To unsubscribe, go to >>> > >>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> > >>>> and follow the instructions there. >>> > >>>> >>> > >>> _______________________________________________ >>> > >>> time-nuts mailing list -- [email protected] >>> > >>> To unsubscribe, go to >>> > >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> > >>> and follow the instructions there. >>> > >>> >>> > >>> >>> > >>> ----- >>> > >>> No virus found in this message. >>> > >>> Checked by AVG - www.avg.com >>> > >>> Version: 2016.0.7227 / Virus Database: 4477/11098 - Release Date: >>> > >>> 12/01/15 >>> > >>> >>> > >> >>> > >> _______________________________________________ >>> > >> time-nuts mailing list -- [email protected] >>> > >> To unsubscribe, go to >>> > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> > >> and follow the instructions there. >>> > >> >>> > > >>> > > >>> > _______________________________________________ >>> > time-nuts mailing list -- [email protected] >>> > To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> > and follow the instructions there. >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
