[time-nuts] Re: Effect of temperature on cheap puck style GNSS antennas?
On Fri, 13 May 2022 03:30:35 -0400, time-nuts-requ...@lists.febo.com wrote: time-nuts Digest, Vol 217, Issue 25 > > Message: 2 > Date: Thu, 12 May 2022 07:01:11 -0600 > From: Bob kb8tq > Subject: [time-nuts] Re: Effect of temperature on cheap puck style > GNSS antennas? > To: Discussion of precise time and frequency measurement > > Message-ID: <805c458d-7630-4ccb-8e40-d56254c45...@n1k.org> > Content-Type: text/plain; charset=utf-8 > > Hi > > >> On May 12, 2022, at 3:21 AM, Lux, Jim wrote: >> >> On 5/11/22 11:50 PM, Matthias Welwarsky wrote: >>> Dear list members, >>> >>> My DIY GPSDO has a rather well defined dependence to the environmental >>> temperature, which correlates almost linearly with a frequency >>> shift of the >>> OCXO. However, at times I see the error against the GNSS >>> reference increasing >>> with its case temperature not warranting such effect. >>> >>> My antenna is one of those cheap, magnetic, active antennas you'd >>> put on a car >>> roof. It's facing south and has full exposure to the sun, obviously. >>> >>> During sunrise I see the TIC error increasing 20ns-30ns over lets say 2000 >>> seconds. The GPSDO case temperature rises, too, during that time >>> as the room temperature increases, but it is only by 0.3°C. >>> >>> I'm wondering if the temperature of the antenna, which of course >>> rises much >>> faster than the room temperature, can have an effect of this magnitude? >> >> >> Very possible. I've seen fairly large changes (nanoseconds over a >> 0-40C temp range) in delay in the LNA and bandpass filter for GNSS >> receivers with temperature. If they're using any sort of ceramic >> filter or ceramic antenna, then that can have a fairly large >> tempco in the time delay. > > The ceramic typically used for antennas is unlikely to have that > much change > over any reasonable temperature range. The ceramic filters are very > different > beasts …. The impact of the antenna should be down in the “couple > of ns” range at most. > > Since this is a “who knows what” antenna, there is no way to be > *sure* of what it’s > doing. A properly designed small / low cost antenna should do pretty well. Before doing anything fancy, I'd be tempted to enclose the GPS puck in a cheap small polystyrene foam beer cooler, to reduce and slow down temperature changes at the puck due to sun and wind, and see how much effect this has. Joe Gwinn ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-le...@lists.febo.com
[time-nuts] Re: Effect of temperature on cheap puck style GNSS antennas?
Hi > On May 12, 2022, at 3:21 AM, Lux, Jim wrote: > > On 5/11/22 11:50 PM, Matthias Welwarsky wrote: >> Dear list members, >> >> My DIY GPSDO has a rather well defined dependence to the environmental >> temperature, which correlates almost linearly with a frequency shift of the >> OCXO. However, at times I see the error against the GNSS reference increasing >> with its case temperature not warranting such effect. >> >> My antenna is one of those cheap, magnetic, active antennas you'd put on a >> car >> roof. It's facing south and has full exposure to the sun, obviously. >> >> During sunrise I see the TIC error increasing 20ns-30ns over lets say 2000 >> seconds. The GPSDO case temperature rises, too, during that time as the room >> temperature increases, but it is only by 0.3°C. >> >> I'm wondering if the temperature of the antenna, which of course rises much >> faster than the room temperature, can have an effect of this magnitude? > > > Very possible. I've seen fairly large changes (nanoseconds over a 0-40C temp > range) in delay in the LNA and bandpass filter for GNSS receivers with > temperature. If they're using any sort of ceramic filter or ceramic antenna, > then that can have a fairly large tempco in the time delay. The ceramic typically used for antennas is unlikely to have that much change over any reasonable temperature range. The ceramic filters are very different beasts …. The impact of the antenna should be down in the “couple of ns” range at most. Since this is a “who knows what” antenna, there is no way to be *sure* of what it’s doing. A properly designed small / low cost antenna should do pretty well. Bob > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-le...@lists.febo.com ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-le...@lists.febo.com
[time-nuts] Re: Effect of temperature on cheap puck style GNSS antennas?
On 5/11/22 11:50 PM, Matthias Welwarsky wrote: Dear list members, My DIY GPSDO has a rather well defined dependence to the environmental temperature, which correlates almost linearly with a frequency shift of the OCXO. However, at times I see the error against the GNSS reference increasing with its case temperature not warranting such effect. My antenna is one of those cheap, magnetic, active antennas you'd put on a car roof. It's facing south and has full exposure to the sun, obviously. During sunrise I see the TIC error increasing 20ns-30ns over lets say 2000 seconds. The GPSDO case temperature rises, too, during that time as the room temperature increases, but it is only by 0.3°C. I'm wondering if the temperature of the antenna, which of course rises much faster than the room temperature, can have an effect of this magnitude? Very possible. I've seen fairly large changes (nanoseconds over a 0-40C temp range) in delay in the LNA and bandpass filter for GNSS receivers with temperature. If they're using any sort of ceramic filter or ceramic antenna, then that can have a fairly large tempco in the time delay. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-le...@lists.febo.com
[time-nuts] Re: Effect of temperature on cheap puck style GNSS antennas?
"During sunrise" Isn't it more likely to be due to changes in the ionosphere during sunrise/set that causes the timing discrepancies. Any changes to the antenna / LNA due to temperature will affect the reception of all satellites so should cancel out. Andy www.g4jnt.com On Thu, 12 May 2022 at 08:33, Matthias Welwarsky wrote: > Dear list members, > > My DIY GPSDO has a rather well defined dependence to the environmental > temperature, which correlates almost linearly with a frequency shift of > the > OCXO. However, at times I see the error against the GNSS reference > increasing > with its case temperature not warranting such effect. > > My antenna is one of those cheap, magnetic, active antennas you'd put on a > car > roof. It's facing south and has full exposure to the sun, obviously. > > During sunrise I see the TIC error increasing 20ns-30ns over lets say 2000 > seconds. The GPSDO case temperature rises, too, during that time as the > room > temperature increases, but it is only by 0.3°C. > > I'm wondering if the temperature of the antenna, which of course rises > much > faster than the room temperature, can have an effect of this magnitude? > > Best regards, > Matthias > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-le...@lists.febo.com > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-le...@lists.febo.com
