Hi Indeed (as I suspected) that 75 MHz filter runs up the total parts cost quite a bit. First thing I’d do is take a look at the board this connects to. Does it already have a narrowband filter (at 75 MHz) on it?
Bob > On Dec 2, 2015, at 10:36 AM, paul swed <[email protected]> wrote: > > 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. _______________________________________________ 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.
