There are many claims made for products that are not true or have no relevance to what they do.
I doubt it does. The cost and complexity of arranging a low pass audio filter would be enormous.
several seriously large and expensive ferrite pots to start with.
I concede it might have a teensy smidgeon of an RF blocker in it. capable of blocking MHz level signals. For all the good that would do.
Thereby hangs your problem.
Less interference, seriously bad attenuation at the top end
No, its a consistent 3dB on my logs.
And is exactly when you DO want to resynch, or it will simply fall back anyway when the S/N ratio drops about 1.5dB below the target margin
similar to mine where I get (after E side switch) a reliable 5.5Mbps or so with an S/N ratio of 9dB +- 1.5db over the day.
An expensive, vulnerable to thunderstorm, waste of money.
Looks like thy have a crude ACTIVE filter on the audio side powered off the lines 100V system.
If you have designed as many as I have, you will know that whilst they work jolly well in the audio band, RF tends to take one look at them and find an alternative route..unless you have extensive ground planes and metal shielding...
:-)
Something like that.
money and
Sick Squid expensive?
Must be looking at something else, that link takes me to a bog standard face plate filter. Phone lines are 50v on hook, ISDN is 110v IIRC but BT don't offer ADSL over ISDN, even though it is possible.
and you think that DC on a phone line is 100v. Oh well if you say so Mr Expert Designer...
I have never designed ANYTHING for a phone line Dave.
Only spent 20 years designing audio equipment. Power amplifiers, hifis, mixing desks, guitar amplifiers..disco consoles, active crossovers. graphic equalisers..VHF and AM radios...video amplifiers, reverberation delay lines..phase shifters.. IF strips for radar..and the power supplies to drive em. Even model R/C equipment..years ago. In short if its analogue design up to 20Mhz, I've pretty much done the lot.
I do know about RF in audio. And how NOT to get the local taxi firm on your Hifi.
I am not so good on RF its true. Only ever build and designed two or three transmitters and 10 or so receivers,
All the ones I have seen have had a number capacitors, a couple of transistor looking things and sometimes (depending on make) several chokes.
What purpose to they all serve?
I though it was 48V or so?
Mostly none.
All you need is an RF choke in the phone line to make sure the phones don't actually short the DSL. Probably a spark arrestor thingie is mandatory, and the normal ring stuff if its a master socket - capacitor and resistor.
I suspect the active ones are largely useless.
The ONLY thing I can remember is something about 100v or 70V AC ring, and there being a DC current on hook. I know that cost we had a pabx that only stuffed out 50v AC and some phones wouldn't ring.
the nearest i got to that was software on a telex card, but that's all different anyay.
So why do they use them when this is a volume mass produced item? .
Thy don't do that for things like TV sets;!...
Y'all need to take a peek at BT SIN 351.
On hook DC will not exceed 70v. Pretty sure that 50v is the nominal voltage, 48v is near as damn it, 100v is plain wrong for a POTS line.
On hook there is very little current flow, off hook there is. Depending on the line card this maybe a variable current and voltage from 30+ mA down to not less than 25mA @ 9v or with newer line cards a 25mA constant current source.
Ringing is 40 to 100v AC 25Hz (+1Hz -5Hz). Some phones are designed to work on 17Hz ringing (as used in other parts of the world) and can't move the hammer fast enough to make the hammer hit the gongs.
+/- 80v mark/space from a fairly high impredance source IIRC. Don't know how call set up is acheived.In article , Dave Liquorice scribeth thus
ISTR that ISDN is around 70 volts...
nominal
ISDN POTS B-)
European ISDN has a nominal 96v DC but I have seen references of up to 120v. US ISDN is around 70v.
Interesting, I've never seen any which are supplied directly with the chip running voltage, because that requires a perfectly matched wall wart, which is going to be expensive when you consider all the variants supplied in different countries. Usually they design for any old wall wart, and then find the cheapest chinese supplier of generic OEM ones.
Another way to spot the SMPSU is to run the device from a variable voltage supply and monitor the current. Start with the right supply voltage and note the current. Turn the supply down a bit (preferably whilst ensuring the device still works), and this will cause a switched mode PSU to draw more current (the opposite of what a resistive load would do). When running over long cat5, you'll need a higher voltage, and I usually try to use 5V or 12V from the PC's power supply. So, to test this, I'll next crank up the supply voltage gradually, monitoring that the current draw drops, and working out the power consumption and checking it doesn't rise (or at least, not by much, and nowhere near as much as it would for a resistive load).
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Dave Liquorice" saying something like:
Or simply extend the UPS Euro outlets to run a couple of 4-way sockets, labelled 'UPS' and plug the router PS into one.
DC should be at -48V. Ringing AC can be getting on for 100 - although more typically about 90VAC
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.