>>Looks like the IF filter to me, with L1/C4 doing the phase shift for the
>>diff input.
>
> Yes, you are right. It's a filter, not a crystal.
>
>>Who knows why they decided to design the TRF with a
>>differential IF input, doesn't make a lot of sense to me. Infineon
>>didn't do that on the TDA5210.
>
> Perhaps for noise margins with lower VCC (2.2V to 3.6V for TRF vs. 5V
> for the TDA). Anyway, I am not going to worry about the physical size,
> except with the note: "smaller board can be made". The lower VCC is
> swinging me back into the TRF camp for now.
>
> By the way, what would be good choices for RF Amps? It will be feeding
> directional antenna if output exceeds FCC limits.
>
Don't know, I used to do them discrete. Picked a nice transistor and had
at it. But this is not cool if you need pre-cert stuff.
--
Regards, Joerg
http://www.analogconsultants.com
Reply by linnix●October 13, 20062006-10-13
Joerg wrote:
> Looks like the IF filter to me, with L1/C4 doing the phase shift for the
> diff input.
Yes, you are right. It's a filter, not a crystal.
> Who knows why they decided to design the TRF with a
> differential IF input, doesn't make a lot of sense to me. Infineon
> didn't do that on the TDA5210.
Perhaps for noise margins with lower VCC (2.2V to 3.6V for TRF vs. 5V
for the TDA). Anyway, I am not going to worry about the physical size,
except with the note: "smaller board can be made". The lower VCC is
swinging me back into the TRF camp for now.
By the way, what would be good choices for RF Amps? It will be feeding
directional antenna if output exceeds FCC limits.
> "Joerg" wrote:
>
>> Hey, the grudges from the Boston tea party are behind us by now :-)))
>
> It is amazing how many times people forget and you get the panic
> phone call in early hours of the morning!
>
> Or I could say that was just a storm in a tea cup, or look at the
> trouble caused by the inability to make a decent cup of tea. Don't
> get me started on alternative namings of holidays, as I believe
> last Monday was the National Cock up day - somebody heading for
> India and missing.
On Thursday, in article
<yotXg.15887$7I1.2684@newssvr27.news.prodigy.net>
notthisjoergsch@removethispacbell.net "Joerg" wrote:
>Hello Paul,
>
>>
>> I hope you realise I reside in UK.
>>
>Hey, the grudges from the Boston tea party are behind us by now :-)))
It is amazing how many times people forget and you get the panic
phone call in early hours of the morning!
Or I could say that was just a storm in a tea cup, or look at the trouble
caused by the inability to make a decent cup of tea. Don't get me
started on alternative namings of holidays, as I believe last Monday was
the National Cock up day - somebody heading for India and missing.
>IIRC the rules say that it doesn't matter where the team mates reside.
I have actually taken part in Circuit Cellar comp before. It is more of
realisng the geograhical spread of a team and its communications let alone
hardware/software being in the right place.
>That's how it should be. The only thing you guys would have to agree on
>is whether it's realise or realize...
> > Currently he 27 MHz CB band might work well, but in a few years during
> > the sun spot maximum, the band will be swamped by CB signals from all
> > over the continent. Some CB operators use 1200 bit/s AX.25 packet
> > radio with unmodified CB transceivers. The AX.25 protocol would also
> > take care of the addressing issue.
>
> > The other problem with the 27 MHz band is that it requires a quite
> > large antenna to get even a half decent antenna efficiency, which can
> > be a problem on the truck, thus an external antenna may be required.
>
> > I would suggest getting a licensed frequency in the VHF/UHF band to
> > avoid the interference from other users. UHF should not be a problem
> > up to 1 km, since the master (office) antenna (and transmitter) can be
> > located at a high place e.g. at the roof of the building.
>
> My suggestion is to use multiple channels of frequencies centered
> around 315MHz. Quarter wave antenna of 250cm should be mountable on
> top of trucks.
Yes, 25cm, of course. I am talking to myself again.
> Using multiple transmitters with different primary
> frequencies, it should cover area of hundred meters.
>
> However, you must follow FCC (or equivalent) guidelines. Namely, no
> other users would complaint. Or you can get a license to override
> other uses. This should be doable for a commerical terminal.
>
> That would dictate the use of RTF6903 over TDA5200, for 315MHz FSK SS.
Reply by Joerg●October 12, 20062006-10-12
Hello Paul,
>
> I hope you realise I reside in UK.
>
Hey, the grudges from the Boston tea party are behind us by now :-)))
IIRC the rules say that it doesn't matter where the team mates reside.
That's how it should be. The only thing you guys would have to agree on
is whether it's realise or realize...
--
Regards, Joerg
http://www.analogconsultants.com
Reply by linnix●October 12, 20062006-10-12
> Currently he 27 MHz CB band might work well, but in a few years during
> the sun spot maximum, the band will be swamped by CB signals from all
> over the continent. Some CB operators use 1200 bit/s AX.25 packet
> radio with unmodified CB transceivers. The AX.25 protocol would also
> take care of the addressing issue.
> The other problem with the 27 MHz band is that it requires a quite
> large antenna to get even a half decent antenna efficiency, which can
> be a problem on the truck, thus an external antenna may be required.
> I would suggest getting a licensed frequency in the VHF/UHF band to
> avoid the interference from other users. UHF should not be a problem
> up to 1 km, since the master (office) antenna (and transmitter) can be
> located at a high place e.g. at the roof of the building.
My suggestion is to use multiple channels of frequencies centered
around 315MHz. Quarter wave antenna of 250cm should be mountable on
top of trucks. Using multiple transmitters with different primary
frequencies, it should cover area of hundred meters.
However, you must follow FCC (or equivalent) guidelines. Namely, no
other users would complaint. Or you can get a license to override
other uses. This should be doable for a commerical terminal.
That would dictate the use of RTF6903 over TDA5200, for 315MHz FSK SS.
Reply by ●October 11, 20062006-10-11
On 11 Oct, in article
<1160582972.090384.128580@c28g2000cwb.googlegroups.com>
me@linnix.info-for.us "linnix" wrote:
>I am drafting designer into the Circuit Cellar design contest, ($10,000
>splits three ways). We will be fitting an RF transponder into a cell
>phone (with the orginal board removed). So, we need experts in the
>following area.
>
>ISM band FSK RF transceiver
> TDA5100/5210
> TRF6903
>FPGA/CPLD LCD controller (100x100)
> Xilinx Spartian/Cool Runner
>ARM
> LM3SXXX (required)
Whilst I have experience with some of that field, the chance to
play with an ARM (Cortex M3) would be interesting.
>I recomend the following list of people to head one of the projects.
>If you are in this list, please indicate if you are willing to commit
>to it. For Ulf, yes, you need to do ARM, even if you work for Atmel.
>Your challenge is to make it portable to AVR. For everyone else,
>please vote for one in each team or write in other candidates. Thanks.
>
>larwe
>Tim Wescot
>Paul Carpenter
>Joerg
>Ulf Samuelsson
I hope you realise I reside in UK.
Whilst it is an honour to be considered and amongst such 'luminaries'
I am currently behind on some projects due to a week of illness and the
major projects (ASIC testers) are expected to last until January.
I will have to bow out due to commercial commitments.
--
Paul Carpenter | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/> PC Services
<http://www.gnuh8.org.uk/> GNU H8 & mailing list info
<http://www.badweb.org.uk/> For those web sites you hate
Reply by linnix●October 11, 20062006-10-11
Additional ideas:
A portable unit can switch between the vehicle base station and
terminal base station. If it's not convienent to move the trucks to
the data dump area, just move the portable unit there.
Don't the trucks all go in/out through a gate? Ideal place for a data
dump zone.
Reply by linnix●October 11, 20062006-10-11
Joerg wrote:
> Hello Linnix,
>
Never mind, TDA5200 is available in single now (digikey), since last
check a few days ago. Perhaps someone is listening.
> ...
> Looks like the IF filter to me, with L1/C4 doing the phase shift for the
> diff input. Who knows why they decided to design the TRF with a
> differential IF input, doesn't make a lot of sense to me. Infineon
> didn't do that on the TDA5210.