|
Andy G4JNT
-80dBc spurii - LUXURY !
On Bell Hill I considered -60dBc good. And more to the point, so did G3VPF operating 20km away LOS, beaming through the beacons to get to the Dx.
That uses a PLL source, so phase noise is not brilliant, but discrete spurii are few. Phase noise is not harmful, except when very strong signals coexist with weak ones. PN has to be worse than terrible before it actually affects signal quality using the modes we do for narrow band work. More significant for the wider band ATVers though.
The 13cm beacon at GB3MHZ generates 320.830MHz using the OZ
beacon system DDS and mixes it with a doubled version of the 1GHz
clock to generate a low phase noise output at 2320.830MHz. Its not
a free lunch however, there a few discrete spurii apparent mostly
down at -80dBc or lower, one or two of which appear in the narrow
band segment around 2320.200.
73
John G3XDY
On 24/11/2022 11:39, Robin Szemeti -
G1YFG via groups.io wrote:
Ah, noted. I hadn't considered the idea of working
downwards to generate LF stuff ... I'm usually trying to work
upwards ;)
It's
used, in the OZ beacon hardware, as the clock for a DDS
that generates up to perhaps 400MHz directly, and higher
via image products and multiplication.
A
DDS allows direct straightforward MFSK modulation, and
introduces virtually zero added phase noise onto that from
the master clock. So use a very good 1GHz drive and PN
goes as 20LOG(Fout / 1GHz) on that.
Beats
the hell out of using the internal PLL clock multiplier in
a lot of DDS devices.
I'm still busy trying to work out why you
would want a 1 GHz reference frequency in the first
place ...
Ah....
Must
be getting old
Misread
the data sheet
Still
good though
And
pricey
5
to 10kHz/V tuning. Is that a DRO based
unit then? The data sheet doesn't say. I
can't see an LC based VCO managing to keep
that sort of stability and have such a low
tuning sensitivity.
Even
at > £100 a pop!
This is what is used in the OZ7IGY Next
Gen beacon platform:
https://www.mouser.co.uk/datasheet/2/94/CVCO55CX-1000-1000-28506.pdf
Not cheap but good PN
performance for a 1GHz standard.
73
John G3XDY
On 23/11/2022 21:48, Dominique Dehays
wrote:
Ge Robin
I recall a good design
by on4iy using a crystek resonator.
If I recall rigth it was
in the ghz range and phase noise was
rigth
73
Dom
--
Robin Szemeti - G1YFG
--
Robin Szemeti - G1YFG
|
|
|
The 13cm beacon at GB3MHZ generates 320.830MHz using the OZ
beacon system DDS and mixes it with a doubled version of the 1GHz
clock to generate a low phase noise output at 2320.830MHz. Its not
a free lunch however, there a few discrete spurii apparent mostly
down at -80dBc or lower, one or two of which appear in the narrow
band segment around 2320.200.
73
John G3XDY
On 24/11/2022 11:39, Robin Szemeti -
G1YFG via groups.io wrote:
toggle quoted message
Show quoted text
Ah, noted. I hadn't considered the idea of working
downwards to generate LF stuff ... I'm usually trying to work
upwards ;)
It's
used, in the OZ beacon hardware, as the clock for a DDS
that generates up to perhaps 400MHz directly, and higher
via image products and multiplication.
A
DDS allows direct straightforward MFSK modulation, and
introduces virtually zero added phase noise onto that from
the master clock. So use a very good 1GHz drive and PN
goes as 20LOG(Fout / 1GHz) on that.
Beats
the hell out of using the internal PLL clock multiplier in
a lot of DDS devices.
I'm still busy trying to work out why you
would want a 1 GHz reference frequency in the first
place ...
Ah....
Must
be getting old
Misread
the data sheet
Still
good though
And
pricey
5
to 10kHz/V tuning. Is that a DRO based
unit then? The data sheet doesn't say. I
can't see an LC based VCO managing to keep
that sort of stability and have such a low
tuning sensitivity.
Even
at > £100 a pop!
This is what is used in the OZ7IGY Next
Gen beacon platform:
https://www.mouser.co.uk/datasheet/2/94/CVCO55CX-1000-1000-28506.pdf
Not cheap but good PN
performance for a 1GHz standard.
73
John G3XDY
On 23/11/2022 21:48, Dominique Dehays
wrote:
Ge Robin
I recall a good design
by on4iy using a crystek resonator.
If I recall rigth it was
in the ghz range and phase noise was
rigth
73
Dom
--
Robin Szemeti - G1YFG
--
Robin Szemeti - G1YFG
|
|
|
Ah, noted. I hadn't considered the idea of working downwards to generate LF stuff ... I'm usually trying to work upwards ;)
It's used, in the OZ beacon hardware, as the clock for a DDS that generates up to perhaps 400MHz directly, and higher via image products and multiplication. A DDS allows direct straightforward MFSK modulation, and introduces virtually zero added phase noise onto that from the master clock. So use a very good 1GHz drive and PN goes as 20LOG(Fout / 1GHz) on that.
Beats the hell out of using the internal PLL clock multiplier in a lot of DDS devices.
I'm still busy trying to work out why you would want a 1 GHz reference frequency in the first place ...
Ah.... Must be getting old Misread the data sheet Still good though And pricey
5 to 10kHz/V tuning. Is that a DRO based unit then? The data sheet doesn't say. I can't see an LC based VCO managing to keep that sort of stability and have such a low tuning sensitivity.
Even at > £100 a pop!
This is what is used in the OZ7IGY Next Gen beacon platform:
https://www.mouser.co.uk/datasheet/2/94/CVCO55CX-1000-1000-28506.pdf
Not
cheap but good PN performance for a 1GHz standard.
73
John
G3XDY
On 23/11/2022 21:48, Dominique Dehays
wrote:
Ge Robin
I recall a good design by on4iy using a crystek
resonator.
If I recall rigth it was in the ghz range and
phase noise was rigth
73
Dom
--
Robin Szemeti - G1YFG
--
Robin Szemeti - G1YFG
|
|
|
Andy G4JNT
It's used, in the OZ beacon hardware, as the clock for a DDS that generates up to perhaps 400MHz directly, and higher via image products and multiplication. A DDS allows direct straightforward MFSK modulation, and introduces virtually zero added phase noise onto that from the master clock. So use a very good 1GHz drive and PN goes as 20LOG(Fout / 1GHz) on that.
Beats the hell out of using the internal PLL clock multiplier in a lot of DDS devices.
I'm still busy trying to work out why you would want a 1 GHz reference frequency in the first place ...
Ah.... Must be getting old Misread the data sheet Still good though And pricey
5 to 10kHz/V tuning. Is that a DRO based unit then? The data sheet doesn't say. I can't see an LC based VCO managing to keep that sort of stability and have such a low tuning sensitivity.
Even at > £100 a pop!
This is what is used in the OZ7IGY Next Gen beacon platform:
https://www.mouser.co.uk/datasheet/2/94/CVCO55CX-1000-1000-28506.pdf
Not
cheap but good PN performance for a 1GHz standard.
73
John
G3XDY
On 23/11/2022 21:48, Dominique Dehays
wrote:
Ge Robin
I recall a good design by on4iy using a crystek
resonator.
If I recall rigth it was in the ghz range and
phase noise was rigth
73
Dom
--
Robin Szemeti - G1YFG
|
|
|
I'm still busy trying to work out why you would want a 1 GHz reference frequency in the first place ...
Ah.... Must be getting old Misread the data sheet Still good though And pricey
5 to 10kHz/V tuning. Is that a DRO based unit then? The data sheet doesn't say. I can't see an LC based VCO managing to keep that sort of stability and have such a low tuning sensitivity.
Even at > £100 a pop!
This is what is used in the OZ7IGY Next Gen beacon platform:
https://www.mouser.co.uk/datasheet/2/94/CVCO55CX-1000-1000-28506.pdf
Not
cheap but good PN performance for a 1GHz standard.
73
John
G3XDY
On 23/11/2022 21:48, Dominique Dehays
wrote:
Ge Robin
I recall a good design by on4iy using a crystek
resonator.
If I recall rigth it was in the ghz range and
phase noise was rigth
73
Dom
--
Robin Szemeti - G1YFG
|
|
|
Andy G4JNT
Ah.... Must be getting old Misread the data sheet Still good though And pricey
5 to 10kHz/V tuning. Is that a DRO based unit then? The data sheet doesn't say. I can't see an LC based VCO managing to keep that sort of stability and have such a low tuning sensitivity.
Even at > £100 a pop!
This is what is used in the OZ7IGY Next Gen beacon platform:
https://www.mouser.co.uk/datasheet/2/94/CVCO55CX-1000-1000-28506.pdf
Not
cheap but good PN performance for a 1GHz standard.
73
John
G3XDY
On 23/11/2022 21:48, Dominique Dehays
wrote:
Ge Robin
I recall a good design by on4iy using a crystek
resonator.
If I recall rigth it was in the ghz range and
phase noise was rigth
73
Dom
|
|
|
Other of their VCO's around that frequency range are coax cavity
based but it doesn't say for this one. The tuning sensitivity is
120kHz/V according to the datasheet, the number quoted below is
for frequency pushing.
73
John G3XDY
On 24/11/2022 10:50, Andy G4JNT wrote:
toggle quoted message
Show quoted text
5 to
10kHz/V tuning. Is that a DRO based unit then? The data
sheet doesn't say. I can't see an LC based VCO managing to
keep that sort of stability and have such a low tuning
sensitivity.
Even
at > £100 a pop!
This is what is used in the OZ7IGY Next Gen beacon
platform:
https://www.mouser.co.uk/datasheet/2/94/CVCO55CX-1000-1000-28506.pdf
Not cheap but good PN performance for a
1GHz standard.
73
John G3XDY
On 23/11/2022 21:48, Dominique Dehays wrote:
Ge Robin
I recall a good design by on4iy using a
crystek resonator.
If I recall rigth it was in the ghz
range and phase noise was rigth
73
Dom
|
|
|
Andy G4JNT
5 to 10kHz/V tuning. Is that a DRO based unit then? The data sheet doesn't say. I can't see an LC based VCO managing to keep that sort of stability and have such a low tuning sensitivity.
Even at > £100 a pop!
This is what is used in the OZ7IGY Next Gen beacon platform:
https://www.mouser.co.uk/datasheet/2/94/CVCO55CX-1000-1000-28506.pdf
Not
cheap but good PN performance for a 1GHz standard.
73
John
G3XDY
On 23/11/2022 21:48, Dominique Dehays
wrote:
Ge Robin
I recall a good design by on4iy using a crystek
resonator.
If I recall rigth it was in the ghz range and
phase noise was rigth
73
Dom
|
|
|
