I am soon to take the Foundation licence test and I'm considering either an
Icom TS50 or the Icom IC - 703.
I dony know enough yet to come to a decision - What in the opinion of the
newsgroup would be a wise choice for a complete Novice ?
I realise the learning will continue AFTER I get the pass certificate - but
I dont want to make an expensive mistake before I even get started....
Any help would be most welcome....
John

On Tue, 30 Nov 2004 17:11:27 +0000 (UTC), "Simon Smith"
wrote:

I am soon to take the Foundation licence test and I'm considering either an
Icom TS50 or the Icom IC - 703.

I would go for the Icom TS50... unless you mean Kenwood TS-50... then
I would go for that.. ;-)

The TS50 is a great radio but lacks modernday filtering/dsp.


Bye Maurice
--
Hamradio: ON4BAM / M0CIL / 9H3Z http://www.on4bam.com/
Travelstories from Alaska, Scotland, South Africa,Iceland,
Faroe Isl., Australia, Norway, Svalbard and IOTA activations

The TS50 is a great radio but lacks modernday filtering/dsp.

===================================

How much, if any, is digital filtering better than the old-fashioned Xtl
filter.
----
Reg

Reg Edwards wrote:
How much, if any, is digital filtering better than the old-fashioned Xtl
filter.

What makes DSP filtering better than Xtal filters is that it is
programmable, not hardwired. The parameters of a DSP filter are
continuously variable although not usually implemented that way
in most amateur radio receivers. Given the processing power
necessary for a filter, one can theoretically have any of a
near-infinite number of filter configurations.

Reg, you could probably program a DSP audio filter that runs on
a PC and outputs audio through the sound card like the ClearSpeech
speaker systems. PSK-31 software packages for the PC certainly contain
a number of DSP filters and other DSP algorithms.

Note that Digital Signal Processing is not limited to filters.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote in message ...
Reg Edwards wrote:
How much, if any, is digital filtering better than the old-fashioned Xtl
filter.

What makes DSP filtering better than Xtal filters is that it is
programmable, not hardwired. The parameters of a DSP filter are
continuously variable although not usually implemented that way
in most amateur radio receivers. Given the processing power
necessary for a filter, one can theoretically have any of a
near-infinite number of filter configurations.

Reg, you could probably program a DSP audio filter that runs on
a PC and outputs audio through the sound card like the ClearSpeech
speaker systems. PSK-31 software packages for the PC certainly contain
a number of DSP filters and other DSP algorithms.

I' ve got 2-3 of those programs. Probably more than that out
there...SBFFT is a DOS DSP program that works real well for a CW or
bandpass/bandstop filter. You can notch, etc , up to six signals at
once, within the stock passband width you select. It's real good for
notching heterodynes, etc...You can cut just a tiny sliver, taking out
the signal, but leave all the rest. I use that for MW sometimes. I
have another DSP program for windows that the guy that wrote MMSSTV
did...It has NR modes, which SBFFT doesn't. Chromasound is pretty
good, but payware...If I use a radio which has DSP in it, such as my
mk2g, I have dual DSP if I want it. Even dual auto-notch, etc. But the
software on the puter is much more powerful overall than the simple
DSP in the 706. All the 706 has is auto notch and NR. Neither of which
I use much at all. Only bandpass filtering is really useful to me, and
most radios don't have it. BTW, all those programs have the various
spectrum graphs, waterfalls, etc... You can see what to notch, and
what freq , etc..Kinda like PSK...
One thing though...DSP is nice and all, and the filters are brick wall
steep, but you can still have blowby problems with near strong
signals, etc...DSP is not near as "bulletproof" as a real hardware
filter. I use both. Get the best of both worlds...As an example...My
830 is pretty good as it is. Variable bandwidth, CW filters, etc...Add
the puter DSP, and it's killer. But in reality, the 830 is good enough
as it is...I have DSP but I don't use it all that much. It's not that
practical to use. For example, my 706 doesn't have a CW filter yet,
and the DSP would be real handy. But the sidetone delay on *sending*
makes it nearly useless. Doesn't do any good to have a 200 cycle
filter if I get tripped up sending due to the delay...:/
I'd have to rig up a separate real time sidetone. And that then means
I would prefer to mute the puter audio when sending...All that mess is
too much hassle...I just get on my old 830 with it's rock solid old
fashioned filters, and be done with it...And the receiver is usually
cleaner to boot, as no artifacts or blowby..MK

On Tue, 30 Nov 2004 18:59:25 +0000 (UTC), "Reg Edwards"
wrote:

How much, if any, is digital filtering better than the old-fashioned Xtl
filter.

Hi Reggie,

DSP, depending on the artistry of the programmer, can do very well
with removing periodic (coherent) noises like birdies and heterodynes.
It can also reduce some incoherent noise. Some filters are adaptable
in that they can recognized (mostly coherent) noises and automatically
reduce them.

As for filtering, DSP filters are capable of skirt selectivity that is
impossible to achieve with any other means. Here too, they are user
configurable (if the option is available) to tailor the skirt slopes
and bandwidth independently and maintain a very low pass band ripple.
All of this is performed through discrete Fourier math, with the
routines in software called IIR or FIR filters. IIR is Infinite and
FIR is Finite Impulse Response.

The software routine, tied to an ADC chip, takes samples and feeding a
delay line, taps that line to feed the same signal (in proportions)
back to the input. Some of this might be compared to the Analog
BiQuad filters but this delay line I speak of actually exists entirely
in software as an algorithm (although early examples in a hybrid
design did this in hardware with greater sophistication than the
BiQuads).

The downside is the quality of the audio has that hollow pipe sound or
exhibits obvious sampling clock signal fed into the audio stream. As
with all digital design, it must be preceded by analog filters to
prevent spectrum folding (high frequency components being translated
into low frequency products) and post filters to smooth out the
product (if the software can't cope).

The sampling rate is the limiting factor. Early DSPs sampling at
least twice the highest audio frequency expected (the Nyquist limit)
established the clock rate and the processor had to perform all the
instructions between those samples. Later DSPs pushed the sampling
rate higher such that you could design filters in the IF range. This
was the second generation DSP of about 10 years ago. Of course, that
IF range was in the 10s of KHz, perhaps as high as 100KHz.
Traditional Analog IF design in this range was already perfectly
suited to razor thin filters with steep skirts, so the advantage was
in the adaptability.

Cheap, external, audio DSPs easily make up for any receiver's lack and
the IF DSP is arguably worth the cost for the beginner.

73's
Richard Clark, KB7QHC

Maurice ON4BAM wrote in message . ..
On Tue, 30 Nov 2004 17:11:27 +0000 (UTC), "Simon Smith"
wrote:

I am soon to take the Foundation licence test and I'm considering either an
Icom TS50 or the Icom IC - 703.

I would go for the Icom TS50... unless you mean Kenwood TS-50... then
I would go for that.. ;-)

The TS50 is a great radio but lacks modernday filtering/dsp.

Which is an *advantage* for a beginner.


Bye Maurice

w3rv

"Brian Kelly" wrote in message
om...
Maurice ON4BAM wrote in message
. ..
On Tue, 30 Nov 2004 17:11:27 +0000 (UTC), "Simon Smith"
wrote:

I am soon to take the Foundation licence test and I'm considering
either an
Icom TS50 or the Icom IC - 703.

I would go for the Icom TS50... unless you mean Kenwood TS-50... then
I would go for that.. ;-)

The TS50 is a great radio but lacks modernday filtering/dsp.

Which is an *advantage* for a beginner.


Definitely. I've seen my students totally overwhelmed by the fancier
radios. If they haven't got one already, I recommend that they start with
something simple, basic, and used while they get their feet wet.

Dee D. Flint, N8UZE

On Tue, 30 Nov 2004 17:11:27 +0000 (UTC), "Simon Smith"
wrote:

What in the opinion of the
newsgroup would be a wise choice for a complete Novice ?

Hi John,

I know the TS-50 (Kenwood) and it is a good, small rig. Try to get
the companion power supply from Germany (sorry, don't know the product
name) which is a switching power supply (equally as small, but
suitable and a lot lighter than big linear supplies).

I realise the learning will continue AFTER I get the pass certificate

The downside with this, or any other "small" rig is that you will
indeed be continuing to learn. This is because there's not enough
buttons and knobs to go with all the functionality and you have to
learn how to navigate their software menus (not always intuitive) and
cryptic displays.

There are two roads that this offers. For someone who doesn't want to
fiddle with knobs and such, you can figure out the menus, set your
options, and simply talk on the rig for ever after. For someone who
does want to tune, tweak, and adjust - you really need something
bigger; and if that means outside of your budget, it then suggests
older.

Another point to consider, if you stay with this hobby long enough,
you will eventually get at least two of everything. So don't approach
a decision thinking you won't be facing that choice again. As such,
buy something affordable that leaves you enough money from your budget
to buy the other things that go with it - mike, key, speaker, antenna
tuner, power meter, and certainly enough transmission line, wire, then
insulators, some rope and pulleys and so on. Oddly enough, most of
these secondary items will be with you longer than your rig. Older
transistorized rigs that still work, will undoubtedly work for as long
as you own them and pass them on.

If you want to bury your hands in the guts, try tube sets. They are
bigger yet, and don't mind your first time mistakes on fixing things.
Plus all the voltages are much higher, and touching the wrong lead
lends a sort of zest to this past time. Cheaper than gambling and you
get the thrills of javelin catching without needing to get out of your
house.

73's
Richard Clark, KB7QHC

Hi John

A very hard decision indeed as it depends on what you want to do with
amateur radio, but need experience to make such a decision!

Have you made contact with other amateurs in your area? Like through a
club? You may be able to do hands on comparison of various radios both
recent and old. You will also then be able to apply this to
understanding what the listed specifications mean and whether they are
important or not. (Like good receiver sensitivity on 80M is pretty
pointless given the amount of general band noise) If you are comparing
DSP the only real good indicator is your own ears!

You could of course buy something super cheap and old, learn from it and
then go to something more expensive..

Cheers Bob VK2YQA

Simon Smith wrote:
I am soon to take the Foundation licence test and I'm considering either an
Icom TS50 or the Icom IC - 703.
I dony know enough yet to come to a decision - What in the opinion of the
newsgroup would be a wise choice for a complete Novice ?
I realise the learning will continue AFTER I get the pass certificate - but
I dont want to make an expensive mistake before I even get started....
Any help would be most welcome....
John