[hpsdr] hpsdr Digest, Vol 11, Issue 12
FRANCIS CARCIA
carcia at sbcglobal.net
Tue Jan 16 07:02:35 PST 2007
Hi All,
ECL is pretty easy to use. All you need to do is treat it like an RF device. Then just follow the loading and transmission rules. When AC logic came out I saw all the old ECL rules surface.
I wonder why nobody has thought of using FETs as switches? The first H mode used an SD5000. Why not look at discrete parts. I have found stuffing too much stuff on one substrate can cause cross talk. I was actually surprised with the performance of the FST3253 at HF. This may take a second transformer but if it was rated for 50 or so watts it should work.
I have a hard time trusting the HP8640B for dynamic ranges over 100 dB. I get the feeling theer is interaction between generators. A friend who has been doing high dynamic range stuff uses a pair of isolation amplifiers after the generators to avoid problems.
lurker frank wa1gfz.
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Today's Topics:
1. Re: An high dynamic QSD front-end (Giancarlo Moda)
2. Re: Phoenix (Ray Anderson)
3. Re: An high dynamic QSD front-end (Marco IK1ODO)
4. Re: An high dynamic QSD front-end (Marco IK1ODO)
5. Re: An high dynamic QSD front-end (Lyle Johnson)
6. Re: An high dynamic QSD front-end (Robert McGwier)
7. ADG901 (Geoff)
8. Re: ADG901 (Dan Andersson)
9. Re: ADG901 (Ahti Aintila)
----------------------------------------------------------------------
Message: 1
Date: Mon, 15 Jan 2007 11:01:05 -0800 (PST)
From: Giancarlo Moda
Subject: Re: [hpsdr] An high dynamic QSD front-end
To: HPSDR Group
Message-ID: <20070115190105.86682.qmail at web37203.mail.mud.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
Hi Bob,
Marco, IK1ODO, has done a very interesting and
welcomed analysis of QSD in SDR. Also Ahti, OH2RZ, has
defined an interesting way to improve QSD.
I would like to report a few comments to your notes
below.
I believe discussions are very important as are way to
exchange ideas and improve designs in the ham or
business field.
Date: Sun, 14 Jan 2007 17:37:06 -0500
From: Robert McGwier
Subject: Re: [hpsdr] An high dynamic QSD front-end
To: Ahti Aintila
Cc: Marco IK1ODO , hpsdr at hpsdr.org
Message-ID: <45AAB092.8020300 at gmail.com>
Content-Type: text/plain; charset=ISO-8859-1;
format=flowed
Congratulations. Very nice analysis, very
straightforward, not
requiring the machinery of Laplace transforms to
understand the reasons
which the "intuition impoverished mathematician" had
to do to gain
intuition. If you study Leif ?sbrink's WSE hardware
you will see the
great lengths he went to do his "transient fix". He
was working very
hard to supply the current from a suboptimal current
source to overcome
the transients problems with the four phase capacitor
pseudo-integrator. He had a heuristic understanding
of the need some
time ago but did not go fully virtual ground, current
mode with the
necessary integrator to solve this in the utterly
simple ISD Ahti has
shown us.
Thank you both for a serious elevation of this
discussion. It really
is
time to build hardware. WARNING: We definitely want
to steer away
from
the FST switches. FROM MEASUREMENT, coupled with DDS
issues, they
are
the source of the increasing noise figure. Marco's
plots, as well as
Phil C's and my measurements of various QSD's using
them show this
inescapable fact.
> It was my understanding that Marco did try to
demonstrate the opposite about QSD noise
I think various pieces of analysis have incorrectly
attributed the measurements but the switches are a
major contributor.
> SDR is an interesting field in radiocommunication
but I feel there is still a lot of work to be done as
we do have to learn on how to do measurements with
this kind of receivers contrary to the analog radio
equipment ...
They solved an early problem and we can thank Gerald
for finding this
part and his very gracious publication in QEX and with
the SDR-1000.
> I would like to underline that I am the ONE that had
the idea, early 1998, to use the Fast Bus Switches
like the FST3125 in mixers to replace diodes and MOS
in particular for the G3SBI H-Mode Mixer. The Idea of
FST use did improve the Tayloe QSD.
But it is time to leave them behind FOREVER.
> Sorry but I do not understand your "FOREVER" in the
abouve phrase. Leave the Forever for all radio project
or FOREVER for SDR ?
I believe we should never close any door to the past
or to the future. I am sure the HPSDR group will
rlease SDR project very advanced going totally with
digital solution ... but we should never forget we are
Amateur Radio and not Business, although there are
many involved in SDR that are also in the industry.
> There are other colleges experimented with recent
switches like the FSA322 ... that may give H-Mode
Mixer with IP3 around +50dBm .... what will be the
value of IP3 in HPSDR?
Thanks and best 73
Gian
I7SWX
73's
Bob
N4HY
____________________________________________________________________________________
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------------------------------
Message: 2
Date: Mon, 15 Jan 2007 11:58:07 -0800
From: "Ray Anderson"
Subject: Re: [hpsdr] Phoenix
To:
Message-ID:
Content-Type: text/plain; charset="us-ascii"
I posted my reply to Lyle's inquiry back around the 1st of the year when
the mail reflector was acting up. So far I haven't heard from anyone
regarding their desire to become involved in or take over the Phoenix
project. As I mentioned, due to other commitments my time available for
involvement with Phoenix is quite limited as well as my temporary lack
of radio lab facilities.
-Ray WB6TPU
>I'm curious as to the status of Phoenix. Has the QSD op-amp been
>chosen? The DDS or other synthesizer? Is a preamp going to be
required
>in any event to minimize oscillator radiation back to the antenna?
>Thanks!
>Lyle KK7P
Lyle-
Phoenix progress has kind of stalled on my end due to unanticipated
drains on my time both at work and in the evenings.
I have been monitoring the list on a daily basis to keep up to speed on
other HPSDR activity (with particular interest in the QSD discussion
related to the Odyssey project).
In addition to a general shortage of time I am also temporarily devoid
of debug/troubleshooting facilities to bring a new design to life.
Hopefully that will resolve itself in the not too distant future.
After quite a bit of contemplation I think that an invitation for
assistance from others who have more immediate time and facilities is in
order so as to not unduly delay the realization of Phoenix now that
Janus and Ozy are on the verge of becoming releasable designs. I've been
delaying the plea for extra involvement in the hope I'd have a large
block of time open up, but for the foreseeable future this is looking
kind of doubtful.
If anyone feels like becoming involved in the development of the Phoenix
board (integrated HF RX and TX) in either actual board design and or
bringup/testing/characterization I'd be more than pleased to have them
become associated with the project. I really dislike having the project
unduly delayed due to my current lack of time and facilities.
Best Regards & 73,
Ray WB6TPU
________________________________
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Message: 3
Date: Mon, 15 Jan 2007 22:28:58 +0100
From: Marco IK1ODO
Subject: Re: [hpsdr] An high dynamic QSD front-end
To: hpsdr at hpsdr.org
Message-ID:
Content-Type: text/plain; charset="us-ascii"
At 23.37 14/01/2007, N4HY wrote:
>It really is time to build hardware.
So I did, spending three months to optimize it.
>WARNING: We definitely want to steer away from the FST
>switches. FROM MEASUREMENT, coupled with DDS issues, they are the
>source of the increasing noise figure. Marco's plots, as well as
>Phil C's and my measurements of various QSD's using them show this
>inescapable fact. I think various pieces of analysis have
>incorrectly attributed the measurements but the switches are a major
>contributor.
>They solved an early problem and we can thank Gerald for finding
>this part and his very gracious publication in QEX and with the SDR-1000.
>But it is time to leave them behind FOREVER.
>
>73's
>Bob
>N4HY
Bob,
why do you say so? I think I measured and demonstrated exactly the
opposite: the switching noise from the FST may be minimized, and the
overall level plan of the receiver has to be considered to reduce the
noise contribution of the opamps. I see no "inexcapable facts".
Please consider the figures that I measured - in some point perhaps
by defect, see http://www.spin-it.com/sdr/IK1ODO_SDR1.html
Low gain audio interface setting (+4dBu f.s.)
RF input level for A/D converter saturation: -3dBm
SFDR: 90dB with -10dBm RF input
Noise floor: -123dBm / 2.4kHz
3' order dynamic range: 105 dB
IIP3: +36dBm
High gain audio interface setting (-10dBu f.s.)
RF input level for A/D converter saturation: -17dBm
SFDR: 100dB with -20dBm RF input
Noise floor: -128dBm / 2.4kHz
3' order dynamic range: 102 dB
IIP3: +25dBm
How many receivers designs get similar figures with such a simple hardware?
I think it's time to go ahead with Phoenix. It will not be the
definitive receiver, but using the ideas of Ahti and my tested
frontend we may get a very nice intermediate solution, at a low cost.
The LO may be derived from I0CG design (AD9951 plus a 500MHz clock);
possibly a PLL in 10kHz (or wider) steps may be better, but it's not
trivial to design it with sufficient spectral purity.
73 - Marco IK1ODO
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Message: 4
Date: Mon, 15 Jan 2007 22:42:14 +0100
From: Marco IK1ODO
Subject: Re: [hpsdr] An high dynamic QSD front-end
To: Jim Miller , hpsdr at hpsdr.org
Message-ID:
Content-Type: text/plain; charset="us-ascii"; format=flowed
At 23.53 14/01/2007, Jim Miller wrote:
>i'm still left puzzled how any of the active integrators deal with all of
>the signals outside their gain bandwidth capability.
>
>they only present a virtual ground to frequencies at which they have
>significant excess gain.
>
>what am i missing?
>
>73
>
>jim ab3cv
Nothing, Jim.
Please have a look at my schematic at
http://www.spin-it.com/sdr/IK1ODO_SDR1.html
The impedance seen from the RF port is always close to 50 Ohm, at any
frequency.
The key is the diplexer after the integrator. Signal offset more than
250kHz from F0 are grounded there. The opamp is not working at all on
HF signals.
I measured the "blocking" dynamic range, defined as the signal level
that causes A/D saturation or significant distortion in the mixer.
For in-band signals it is -3dBm (for 4Vrms audio out to the EMU); at
1MHz from the tuning frequency +10dBm are needed, then the protection
diodes in the FST start conducting...
The opamp must not see signals outside it's bandwidth. I think I
demonstrated it. Transients out of the QSD reach hundreds of mV with
spectral components in the GHz range; nothing that an audio opamp
could withstand. Blocking them in the diplexer stabilizes the mixer
output impedance and avoids distortion in the opamp.
73 - Marco IK1ODO
------------------------------
Message: 5
Date: Mon, 15 Jan 2007 13:46:32 -0800
From: Lyle Johnson
Subject: Re: [hpsdr] An high dynamic QSD front-end
To: Marco IK1ODO
Cc: hpsdr at hpsdr.org
Message-ID: <45ABF638.3060204 at wavecable.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> I think it's time to go ahead with Phoenix.
Here is an heretical thought: what if we used the QSD at a fixed IF
frequency and thus didn't need a quadrature, wideband injection source?
That might make a PLL - or even a DDS - solution practical or easier.
If the revised QSD works well above 30MHz, we can use a high IF to ease
image rejection and we wouldn't need much in the way of an IF filter, so
we can still use the QSD to get the 200 kHz or so of spectrum display we
have come to expect from this sort of design.
We need something in front of the QSD to suppress LO radiation, and the
"front end" filters and whatnot are going to be required as well. An
H-mode mixer will preserve the dynamic range characteristics we want.
73,
Lyle KK7P
------------------------------
Message: 6
Date: Mon, 15 Jan 2007 17:27:54 -0500
From: Robert McGwier
Subject: Re: [hpsdr] An high dynamic QSD front-end
To: Giancarlo Moda
Cc: HPSDR Group
Message-ID: <45ABFFEA.9070804 at gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hello Gian:
Thank you for your many contributions in the mixer area, to the N2PK VNA
group (both of mine use your circuit boards), and more. Here is what I
know from my own experience, measurements done by Phil Covington, Phil
Harman, and others. From several QSD's I have measured and have seen
measured the rise in noise figure from (say) 14 to 54 MHz. I see that
Marco has done the same with his very nice work. In each case, the
results are similar, if not identical to those I have measured or others
have measured. In those cases where I have seen these kinds of mixers
done without the FST switches, but with different parts, there is <such rise in noise figure>>. Marco's work has one thing different from
all of the other ISD implementations I have seen. It uses the FST
switches you discovered for us. ;-). Marco's circuit has the rise in
NF which is NOT present in those ISD's I have seen measured which do NOT
have the FST's. I am certain Marco is not sloppy and his work is
excellent and I am taking his graphs as the absolute truth. The logical
implication from this is immediate. The FST switches are the cause of
the rise. I would like to minimize the amount of gain needed to make
the receiver usable at 10 and 6 meters.
I acknowledge your work and that of Marco. I am giving my opinions on
the best way to proceed, fully aware of all of this work. I read this
group every day and am grateful for all of the wonderful contributions
and sharing.
73's
Bob
Giancarlo Moda wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Bob,
>
> Marco, IK1ODO, has done a very interesting and
> welcomed analysis of QSD in SDR. Also Ahti, OH2RZ, has
> defined an interesting way to improve QSD.
>
> I would like to report a few comments to your notes
> below.
> I believe discussions are very important as are way to
> exchange ideas and improve designs in the ham or
> business field.
>
> Date: Sun, 14 Jan 2007 17:37:06 -0500
> From: Robert McGwier
> Subject: Re: [hpsdr] An high dynamic QSD front-end
> To: Ahti Aintila
> Cc: Marco IK1ODO , hpsdr at hpsdr.org
> Message-ID: <45AAB092.8020300 at gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
>
> Congratulations. Very nice analysis, very
> straightforward, not
> requiring the machinery of Laplace transforms to
> understand the reasons
> which the "intuition impoverished mathematician" had
> to do to gain
> intuition. If you study Leif ?sbrink's WSE hardware
> you will see the
> great lengths he went to do his "transient fix". He
> was working very
> hard to supply the current from a suboptimal current
> source to overcome
> the transients problems with the four phase capacitor
>
> pseudo-integrator. He had a heuristic understanding
> of the need some
> time ago but did not go fully virtual ground, current
> mode with the
> necessary integrator to solve this in the utterly
> simple ISD Ahti has
> shown us.
>
> Thank you both for a serious elevation of this
> discussion. It really
> is
> time to build hardware. WARNING: We definitely want
> to steer away
> from
> the FST switches. FROM MEASUREMENT, coupled with DDS
> issues, they
> are
> the source of the increasing noise figure. Marco's
> plots, as well as
> Phil C's and my measurements of various QSD's using
> them show this
> inescapable fact.
>
>
>> It was my understanding that Marco did try to
>>
> demonstrate the opposite about QSD noise
>
>
> I think various pieces of analysis have incorrectly
> attributed the measurements but the switches are a
> major contributor.
>
>
>> SDR is an interesting field in radiocommunication
>>
> but I feel there is still a lot of work to be done as
> we do have to learn on how to do measurements with
> this kind of receivers contrary to the analog radio
> equipment ...
>
>
> They solved an early problem and we can thank Gerald
> for finding this
> part and his very gracious publication in QEX and with
> the SDR-1000.
>
>
>> I would like to underline that I am the ONE that had
>>
> the idea, early 1998, to use the Fast Bus Switches
> like the FST3125 in mixers to replace diodes and MOS
> in particular for the G3SBI H-Mode Mixer. The Idea of
> FST use did improve the Tayloe QSD.
>
> But it is time to leave them behind FOREVER.
>
>
>> Sorry but I do not understand your "FOREVER" in the
>>
> abouve phrase. Leave the Forever for all radio project
> or FOREVER for SDR ?
>
> I believe we should never close any door to the past
> or to the future. I am sure the HPSDR group will
> rlease SDR project very advanced going totally with
> digital solution ... but we should never forget we are
> Amateur Radio and not Business, although there are
> many involved in SDR that are also in the industry.
>
>
>> There are other colleges experimented with recent
>>
> switches like the FSA322 ... that may give H-Mode
> Mixer with IP3 around +50dBm .... what will be the
> value of IP3 in HPSDR?
>
> Thanks and best 73
>
> Gian
> I7SWX
>
> 73's
> Bob
> N4HY
>
>
>
>
> ____________________________________________________________________________________
> Finding fabulous fares is fun.
> Let Yahoo! FareChase search your favorite travel sites to find flight and hotel bargains.
> http://farechase.yahoo.com/promo-generic-14795097
> _______________________________________________
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>
>
--
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"If you board the wrong train, it is no use running along the
corridor in the other direction. " - Dietrich Bonhoeffer
------------------------------
Message: 7
Date: Tue, 16 Jan 2007 15:29:49 +1100
From: Geoff
Subject: [hpsdr] ADG901
To: HPSDR Group
Message-ID: <45AC54BD.2050803 at ozemail.com.au>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi Guys,
A couple of numpty questions (I fix machines for a living). Has
anybody looked at the Analog Devices ADG901 as a QSD Switch? I can?t
recall seeing it on the list. Has anybody identified a class of
flip-flops suitable for QSD service above 30 or 40 MHz?
73 de Geoff vk2tfg.
------------------------------
Message: 8
Date: Tue, 16 Jan 2007 10:28:10 +0000
From: Dan Andersson
Subject: Re: [hpsdr] ADG901
To: hpsdr at hpsdr.org
Message-ID: <200701161028.10988.dan.andersson at ieee.org>
Content-Type: text/plain; charset="iso-8859-1"
On Tuesday 16 January 2007 04:29, Geoff wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Guys,
> A couple of numpty questions (I fix machines for a living). Has
> anybody looked at the Analog Devices ADG901 as a QSD Switch? I can?t
> recall seeing it on the list. Has anybody identified a class of
> flip-flops suitable for QSD service above 30 or 40 MHz?
>
> 73 de Geoff vk2tfg.
>
Geoff,
The ADG901 is on the slow side for Ton and Toff.
=== message truncated ===
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