Topics

SAW Filter limitations

bhhoyer@...
 

The UDR has a SAW Filter in both the transmit and receive paths. We are currently using a 440MHz filter with a 19MHz BW, meaning we are 3db down at 430.5MHz and 449.5MHz.

I have been searching for 20MHz filters and have found no reasonable cost solutions. I will be traveling to China later this year to look into the cost (MOQ really) of having SAW filters made to our specification.

Looking at the ARRL BandPlan for 70cm, ATV is up to 432 and the top of the band is for Voice repeaters. Many countries only go up to 440.

The question for the group is, how does this affect your planned deployment? Is it a real issue for production.

Thanks,
Bryan K7UDR

Andre <pe1rdw@...>
 

op 17-03-14 16:50, bhhoyer@... schreef:
 

The UDR has a SAW Filter in both the transmit and receive paths. We are currently using a 440MHz filter with a 19MHz BW, meaning we are 3db down at 430.5MHz and 449.5MHz.


I have been searching for 20MHz filters and have found no reasonable cost solutions. I will be traveling to China later this year to look into the cost (MOQ really) of having SAW filters made to our specification.

Looking at the ARRL BandPlan for 70cm, ATV is up to 432 and the top of the band is for Voice repeaters. Many countries only go up to 440.

The question for the group is, how does this affect your planned deployment? Is it a real issue for production.

Thanks,
Bryan K7UDR
All 9k6 AX.25 channels in the Netherlands are between 430.400 and 431.025 and german duplex ax.25 channels have input between 430.400 and 430.5875 and output between 439.800 and 439.9875.

So there would be some limitation if the 19 MHz SAW filter is used in this configuration.

73 de Andre PE1RDW

John Ronan <jpronans@...>
 

On 17/03/14 16:05, Andre wrote:
op 17-03-14 16:50, bhhoyer@... schreef:
 

The UDR has a SAW Filter in both the transmit and receive paths. We are currently using a 440MHz filter with a 19MHz BW, meaning we are 3db down at 430.5MHz and 449.5MHz.


I have been searching for 20MHz filters and have found no reasonable cost solutions. I will be traveling to China later this year to look into the cost (MOQ really) of having SAW filters made to our specification.

Looking at the ARRL BandPlan for 70cm, ATV is up to 432 and the top of the band is for Voice repeaters. Many countries only go up to 440.

The question for the group is, how does this affect your planned deployment? Is it a real issue for production.

Thanks,
Bryan K7UDR
All 9k6 AX.25 channels in the Netherlands are between 430.400 and 431.025 and german duplex ax.25 channels have input between 430.400 and 430.5875 and output between 439.800 and 439.9875.

So there would be some limitation if the 19 MHz SAW filter is used in this configuration.

73 de Andre PE1RDW

It is a similar situation here in Ireland, and I guess throughout all of IARU Region 1. 

Regards
John
EI7IG

bhhoyer@...
 

We could do a UDRX-430.

there is a 20MHz 431 Filter (421-441). Takes care of the bottom of the US Band as well

It's in a different package (of course) so we'd end up building 440s in mass then reworking the filters.

Might be a small upcharge of 20-25 USD

Bryan K7UDR

Steve <yahoo-udr@...>
 

How does this discussion affect digital voice (DV) and digital data (DD) modes in the USA? Do DV repeater operators always enable DD capability? Or, are there separate DD repeaters? Do the repeater operators follow the ARRL or other local band plans?

Steve

---------- Original Message ----------
[ Sent by bhhoyer@... at 03/17/2014 10:27 AM ]

We could do a UDRX-430.

there is a 20MHz 431 Filter (421-441). Takes care of the bottom of the US Band as well


It's in a different package (of course) so we'd end up building 440s in mass then reworking the filters.


Might be a small upcharge of 20-25 USD


Bryan K7UDR

"John D. Hays" <john@...>
 

Hi Steve,

Currently, the only DD network implementation is 128 kbps on 23 cm from Icom (ID-1 terminals, and RP-2D access point) and is half duplex (no repeaters).  The UDRX will change this, as it will permit DD at data rates from 4.8k to the top data rate (estimated to reach 100k+) of the radio using 70cm band(s). In the US we are limited to a 100 kHz channel.

In the Icom architecture DD is always a separate band module.  With the UDRX we have the potential to run both DD and DV on the same module (at 4800bps).

It may also be possible to build a repeater having 100 kHz channels using the UDRX. (Either bonding 4 adjacent 25 kHz channels at 440 band or using a split in the 430 band.)

DV (which includes a slow data subchannel) is typically simplex, repeated, or simplex access point (hotspot).  This is  a 6.25 kHz channel (or repeater pair).  In the US DV repeaters usually are following the local band plan.  Here in Western Washington (State) we use high in/low out for our repeater pairs and the bandplan has 12.5kHz and 25kHz pairs. 


John D. Hays
K7VE
PO Box 1223, Edmonds, WA 98020-1223 
  






On Mon, Mar 17, 2014 at 11:01 AM, Steve <yahoo-udr@...> wrote:
 

How does this discussion affect digital voice (DV) and digital data (DD)
modes in the USA? Do DV repeater operators always enable DD capability?
Or, are there separate DD repeaters? Do the repeater operators follow
the ARRL or other local band plans?

Steve

"Michael E Fox - N6MEF" <n6mef@...>
 

In Northern California, packet and other data activity is in the 433, 434 and 438 range, with wideband channels in the upper of those two ranges.  This is where we would intend to use the device.

 

http://ncpa.n0ary.org/ncpabandplan.html

 

Michael

N6MEF

 

 

From: UniversalDigitalRadio@... [mailto:UniversalDigitalRadio@...] On Behalf Of bhhoyer@...
Sent: Monday, March 17, 2014 10:27 AM
To: UniversalDigitalRadio@...
Subject: Re: [UniversalDigitalRadio] SAW Filter limitations

 

 

We could do a UDRX-430.

 

there is a 20MHz 431 Filter (421-441). Takes care of the bottom of the US Band as well

 

It's in a different package (of course) so we'd end up building 440s in mass then reworking the filters.

 

Might be a small upcharge of 20-25 USD

 

Bryan K7UDR

Steve Stroh N8GNJ <steve.n8gnj@...>
 

This view is probably heretical, but here goes.

The US band plan is largely an accident of a lot of spectrum chasing a small use base, adopted in a very different time, assuming very different technology. Thus, allocation of multiple 6 MHz channels that go unused in most of the US.

And, of course, Line A, which I seem to be forever cursed to live North of... in my latest location, less than a few miles, which rules out 420-430 in parts of the US.

And in a few really rare locations like San Diego and Atlanta, interference from our US Government spectrum landlords.

So, maximum spectrum flexibility within 420 - 450 would be best.

My point is to assume very little about historical uses of 420-450 MHz, especially given that 100 KHz channels will be used - I think it's safe to assume that there will be demand in much of the US (South of Line A) that will want to be using 420-430 MHz, so plan on that variant of the UDRX.

Thanks,

Steve




On Mon, Mar 17, 2014 at 8:50 AM, <bhhoyer@...> wrote:
 

The UDR has a SAW Filter in both the transmit and receive paths. We are currently using a 440MHz filter with a 19MHz BW, meaning we are 3db down at 430.5MHz and 449.5MHz.


I have been searching for 20MHz filters and have found no reasonable cost solutions. I will be traveling to China later this year to look into the cost (MOQ really) of having SAW filters made to our specification.

Looking at the ARRL BandPlan for 70cm, ATV is up to 432 and the top of the band is for Voice repeaters. Many countries only go up to 440.

The question for the group is, how does this affect your planned deployment? Is it a real issue for production.

Thanks,
Bryan K7UDR


"Michael E Fox - N6MEF" <n6mef@...>
 

Also, I’m an “appliance operator” so I don’t understand the purpose of the
filter. But I wonder why the radio would have a limitation that other
amateur radios in the 440 band don’t have. Is this limitation necessary?



Our existing 440 radios are supplemented with cavity filters at sites where
that is needed, just like any radio would be expected to have. One site, in
particular, will probably require the two port version so an isolator can
also be used, just like any repeater would be expected to use. This is
required regardless of how well the radio rejects out-of-band stuff because
we must operate near (physically and frequency-wise) other amateur radios.



Michael

N6MEF





In Northern California, packet and other data activity is in the 433, 434
and 438 range, with wideband channels in the upper of those two ranges.
This is where we would intend to use the device.

http://ncpa.n0ary.org/ncpabandplan.html

Michael

N6MEF



From: UniversalDigitalRadio@...
[mailto:UniversalDigitalRadio@...] On Behalf Of
bhhoyer@...
Sent: Monday, March 17, 2014 10:27 AM
To: UniversalDigitalRadio@...
Subject: Re: [UniversalDigitalRadio] SAW Filter limitations



We could do a UDRX-430.

there is a 20MHz 431 Filter (421-441). Takes care of the bottom of the US
Band as well

It's in a different package (of course) so we'd end up building 440s in
mass then reworking the filters.

Might be a small upcharge of 20-25 USD

Bryan K7UDR

bhhoyer@...
 

The filter is required to suppress carrier feedthru on the TX side in the 350-380 range (Fc-IF). On the receive side it's a nice to have.

We are working towards commercial certification, so some of our internal design goals are tighter than what is typically found in Ham gear.

bhhoyer@...
 

Thanks to all who contributed.

We have a couple of inquiries in for custom filters, the NRE looks reasonable.

In the mean time we'll move forward with the current design and plan on a UDRX-430 for region 1 and 3.

Cheer,
Bryan K7UDR

kdcarlso@...
 

Is it possible to use two narrower filters switched for the high and low end of the band?

 

Dave

KA2OQZ

marklfriedlander@...
 

John,

I have a question in connection with your comment, "Currently, the only DD network implementation is 128 kbps on 23 cm from Icom (ID-1 terminals, and RP-2D access point) and is half duplex (no repeaters).  The UDRX will change this, as it will permit DD at data rates from 4.8k to the top data rate (estimated to reach 100k+) of the radio using 70cm band(s). In the US we are limited to a 100 kHz channel."

Will the DD data rate be user configurable? If so, in what increments?

Thanks & 73
Mark KV4I