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ON TOPIC ! A quick brain teaser.

R

Rich Grise

Jan 1, 1970
0
But there is. From first principles.


It wasn't doing it as well as it should have.

In what respect? Losing blips? Wrong range? ?????
Imagine a classic radar display and how it's supposed to work.

Yeah, I know all that, but you haven't even said what the _symptoms_
are that we're supposed to be diagnosing!

Thanks,
Rich
 
R

Rich Grise

Jan 1, 1970
0
LOL !

It's a cute one.

It took me only minutes to see the issues ( and the solution ) but I did have a
display to view too.

So, WHAT THE F**** WERE YOU SEEING ON IT?

Thanks,
Rich
 
J

john jardine

Jan 1, 1970
0
Eeyore said:
To 'connect' ???? What do you mean ?



None at all. It was blisteringly fast at least initially. It may have slowed
down a bit since. I'm synching at 8128/448 and it doesn't get any faster than
that with BT's gear.

http://www.adslguide.org.uk/tools/speedtest.asp
Gives me 5464/378 kbps currentyl

What are you coneecting with ? Details and stuff, router stats etc.....

Graham
Well, I bought a D-Link ADSL modem (DSL 300T). Self tests fine. When online
runs at the usual 6Mbits/sec. Just very difficult to get online with IDnet
in the first place (PC is only occasionally switched on). "The host, mail at
idnet could not be found", or "Server not found", (Outhouse express, Opera)
takes numerous attempts. Been suggested I may now need to buy an "always on"
router.
john
 
P

Phil Allison

Jan 1, 1970
0
"Eeyore"

Ok - so what was the fix then ?



** Its a FUCKING ASININE **** TROLL **** !!!

- you ASD fucked pile of pommy shit .






....... Phil
 
E

Eeyore

Jan 1, 1970
0
Richard said:
Classic? A-scan, B-scan, or PPI?

PPI. I kind of imagined that's the one most ppl would be familiar with.

Graham
 
E

Eeyore

Jan 1, 1970
0
Rich said:
Yeah, I know all that, but you haven't even said what the _symptoms_
are that we're supposed to be diagnosing!

You should be able to derive that from the circuit description.

It wouldn't be a brain teaser otherwise. :~)

Graham
 
E

Eeyore

Jan 1, 1970
0
john said:
Well, I bought a D-Link ADSL modem (DSL 300T). Self tests fine. When online
runs at the usual 6Mbits/sec. Just very difficult to get online with IDnet
in the first place (PC is only occasionally switched on).

This is a USB modem presumably ?

"The host, mail at
idnet could not be found", or "Server not found", (Outhouse express, Opera)
takes numerous attempts. Been suggested I may now need to buy an "always on"
router.

I haven't actually used my USB modem with Idnet but I can't see why there should
be any problem. My router authenticates just fine, connection established in a
few seconds.

The mail issue possibly won't be connectivity at all in fact.

What settings can you access with your modem ?

Graham
 
E

Eeyore

Jan 1, 1970
0
Phil said:
"Eeyore"


** Its a FUCKING ASININE **** TROLL **** !!!

- you ASD fucked pile of pommy shit .

So you admit you don't have a clue then. Excellent. :~)

Graham
 
P

Phil Allison

Jan 1, 1970
0
" Graham Stevenson = Pommy TROLL from Hell "



** It's an ASININE FUCKING *** TROLL *** !!!


IGNORE THE BIPOLAR, ASD FUCKED POMMY **** !!!





......... Phil
 
E

Eeyore

Jan 1, 1970
0
Phil said:
" Graham Stevenson = Pommy TROLL from Hell "

** It's an ASININE FUCKING *** TROLL *** !!!

IGNORE THE BIPOLAR, ASD FUCKED POMMY **** !!!

Can I pull your strings some more ?

It's quite amusing.

Graham
 
P

Phil Allison

Jan 1, 1970
0
" Graham Stevenson = Pommy TROLL from Hell "



** It's an ASININE FUCKING *** TROLL *** !!!


IGNORE THE BIPOLAR, ASD FUCKED POMMY **** !!!






......... Phil
 
F

Frank Bemelman

Jan 1, 1970
0
Eeyore said:
UK actually. Essex in fact.

Bugger. A perfectly good chance to start another 5000+ thread
shot to pieces ;)
 
E

Eeyore

Jan 1, 1970
0
Frank said:
Bugger. A perfectly good chance to start another 5000+ thread
shot to pieces ;)

LOL !

Was it Raytheon you had in mind ?

Graham
 
R

Rich Grise

Jan 1, 1970
0
PPI. I kind of imagined that's the one most ppl would be familiar with.

The yoke rotator belt was broken? ;-)

Thanks,
Rich
 
Eeyore said:
This is a USB modem presumably ?



I haven't actually used my USB modem with Idnet but I can't see why there should
be any problem. My router authenticates just fine, connection established in a
few seconds.

The mail issue possibly won't be connectivity at all in fact.

What settings can you access with your modem ?

Graham


Thanks. The modem connects to the PC network socket (no USB) and has a
"web page" built in where about 20 meaningless TLA assigned values can
be altered. IDnet told me today I might have a "line problem" so will
pursue this with them.
(mind'st you, they may be assuming all PCs and modems run 24 hours a
day) .
john
 
E

Eeyore

Jan 1, 1970
0
Thanks. The modem connects to the PC network socket (no USB) and has a
"web page" built in where about 20 meaningless TLA assigned values can
be altered. IDnet told me today I might have a "line problem" so will
pursue this with them.
(mind'st you, they may be assuming all PCs and modems run 24 hours a
day) .

No way are they assuming that.

I've used a USB modem with no problems.

What are these 'TLA assigned values' btw ?

Is there no connection status screen ?

Graham
 
Eeyore said:
[email protected] wrote:
[...]
Thanks. The modem connects to the PC network socket (no USB) and has a
"web page" built in where about 20 meaningless TLA assigned values can
be altered. IDnet told me today I might have a "line problem" so will
pursue this with them.
(mind'st you, they may be assuming all PCs and modems run 24 hours a
day) .

No way are they assuming that.

I've used a USB modem with no problems.

What are these 'TLA assigned values' btw ?

Is there no connection status screen ?

Graham

(it's a network modem)
Sample TLA's from just one of it's setup pages ..." LLC SCR PCR QOS VCI
VPI" and I won't even mention the FLA's :)
The connection status tests always passed local tests. US DS line
attenuation (dBs) always OK but tests ultimately failed on inability to
link to IDNET servers. (exactly same problems I had with my Orange
account).

Late news ...
Just had email apologies from IDNET saying they've discovered
"authentication problems at peak times" and this evening have installed
new hardware.
For the first time in weeks, I've connected with no problem.

(somewhat stunned I've had both action and honesty, from a service
supplier ! )
john
 
J

joseph2k

Jan 1, 1970
0
Eeyore said:
You should be able to derive that from the circuit description.

It wouldn't be a brain teaser otherwise. :~)

Graham

From what i have read so far, it is suggestive of a dead electrolytic cap
taking with it a ramp / curve converting diode / transistor. These cause
problems with the range gain controlled amplifiers, in offset and
"linearity" of the ramp.

Please remember that over the phone 'e did not yet, necessarily, have access
to the schematics or the PPI display. Just the same 'e probably took a
good parts kit with him, in expectation have having appropriate parts or
substitutes for the deceased parts.
 
E

Eeyore

Jan 1, 1970
0
Eeyore said:
[email protected] wrote:
[...]
Thanks. The modem connects to the PC network socket (no USB) and has a
"web page" built in where about 20 meaningless TLA assigned values can
be altered. IDnet told me today I might have a "line problem" so will
pursue this with them.
(mind'st you, they may be assuming all PCs and modems run 24 hours a
day) .

No way are they assuming that.

I've used a USB modem with no problems.

What are these 'TLA assigned values' btw ?

Is there no connection status screen ?

Graham

(it's a network modem)
Sample TLA's from just one of it's setup pages ..." LLC SCR PCR QOS VCI
VPI" and I won't even mention the FLA's :)

Well..... I know what VCI and VPI are but don't recognise the others.

The connection status tests always passed local tests. US DS line
attenuation (dBs) always OK

What attenuations do you have ?

but tests ultimately failed on inability to
link to IDNET servers. (exactly same problems I had with my Orange
account).

Late news ...
Just had email apologies from IDNET saying they've discovered
"authentication problems at peak times"

Funny that !

I had an authentication problem with them for the first time yesterday evening @
around 6 pm. I rebooted everything and it was then ok but I did see the problem.


and this evening have installed
new hardware.
For the first time in weeks, I've connected with no problem.

(somewhat stunned I've had both action and honesty, from a service
supplier ! )

They're very straight. You get no nonsense from them.

Graham
 
F

Fred Bloggs

Jan 1, 1970
0
Eeyore said:
The strain gauge thread reminded me of a product with an 'issue' I was once
asked to take a look at.

It was the receiver section of a marine radar.

The detector was followed by several variable gain stages. These were wideband
IC amplifiers made by Ferranti ( now Zetex ) with a control current / voltage
that varied each IC's gain over about something like a 12-15dB range. The
control ports were driven in parallel so that gain was swept equally between all
the devices.

They were at least 6 of these cascaded to provide the necessary gain before the
signal went off for further processing.

After the pulse was transmitted ( and the receiver input clamped ) the gain was
ramped up with a triangle waveform to provide the necessary low gain for near
targets and higher gain for distant targets.

I took one look at the schematic, grinned and said I could fix it.

What problems ( not less than 2 of them ) were they encountering ?

Graham

You have to be demented to think this so-called brain teaser has any
informational content whatsoever: a crummy little marine radar, ppi
display, detector of unknown specification, a gain cascade of unknown
specification, and a "triangle waveform"- don't you mean sawtooth?- the
phone call in the middle of the night, your toothless grin, and a bunch
of other troll trash. No one is going to use a wideband video amp that
does not have logarithmic gain control characteristic, so that has
little do with causing any intrinsic problems. The compromise here is
how to go about maintaining a constant return S/N independent of range
when the attenuation is due to two distinct phenomena: the usual
spherical spreading loss everyone is familiar with by way of the radar
equation varying as LOG(R), and the atmospheric absorption loss varying
directly as R, loss understood to be in dB. You did say this is a marine
radar which I take to mean surface object detection out to the horizon,
making it short range, so the spherical spreading is predominant.
 
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