As soon as the cell phone turned on, it looked for rhythm, and crystallized was the rhythmist who never showed up. He didn't talk, but the whole system had to listen to it。
I fixed a stm32 development board last week, running through usb communications, and finally found it was not a procedural issue, but a small crack under the welded 8mhz sticker next to it, with thermal swelling a few times, and the frequency drifting directly to ±80 ppm, which the usb agreement required to fit within £1 000 ppm, but the actual handshake phase shivering — it was not bad, it was just not allowed。
Many people think that it's "tick-and-tock" when it's plugged in, but it doesn't work at all. It's a very thin piece of stone, with silver on both sides, like a little mirror. And what really moved it was the back camera in the chip and the two little caps next to it, and it was a closed ring. The reverse camera provides a magnification, and the capacitor determines the frequency at which it wants to "knock the hand," and the jingle itself is only responsible for saying, "okay, that's the frequency, i'm not even close to it."。
Why did ishio-young choose the frequency? Because it's cut from a very sensitive angle. The at cut is the most common, like a watermelon, with a tilt and a different taste. The chips cut out by at, the temperature changes, the frequency changes very little, and they can also do high-intensity transliteration -- for example, the 8 mhz of the base frequency, with a little circuit design, so that 48 mhz can be steadily exported, save the back multiple frequency and a series of shakes. However, if it is crooked, or if it is grinding 0. 1 micrometres thick, it is assumed that 8 mhz may become 7. 9996 mhz, each of which would have to be in the incubator for 24 hours before leaving the plant, otherwise it would have floated。
Welding on the board doesn't mean everything's fine. The most ridiculous time i've ever seen is when a colleague puts a crystal vibrate at the top of the pcb, screws four screws, slightly bending the plate, crystal vibrating, and falls 15 ppm directly. Later, the middle position was changed and the stress tank was released to stabilize. There is also a line, with two lines vibrating to the mmu, even one cm more, which gives the parasitic caps an additional 0. 3 pf, combined with the load of the capacitor, with the frequency down. It's not a good time for you to change software. It doesn't want to run like you said。
The precision of this thing, it's not just a 10 ppm. I looked at the same 25 mhz crystal oscillation table of the three manufacturers, with 25 °c measured deviations of +8. 2, -9. 7 and +0. 3 ppm; but in the -40 °c environment box, three floated to -32, -18 and -5 ppm. The temperature coefficient is not a straight line, but a parabolic line with the vertebrae of the at cut at 25°c, so constant temperature is not the same as low temperature. Some of the industrial panels - 40~85°c - resulted in a powering outside the house in the winter and rtc walked for four minutes a day - not a chip problem, but a crystallized turn in the cold zone。
Now the new difference is crystallized, using the lvds signal, walking along two lines, and the noise coming in the road is offset by one plus one minus. But it is demanding of the pcb, with differential resistance stuck 100 times to death, with a long line of no more than 50 millennia, or the receiving end is locked as soon as the eye map blooms. We tried to put lvds crystal welding on a regular fr-4 board, without resistance to control, and the high-speed adc sampling rate led to a miscalculation of the data, and the pcb redoed to understand what was meant by “sign integrity is not genre”。
The programmable crystal vibrate vcxo, which is able to adjust the frequency by voltage, looks cool, and the actual range is around ±100 ppm, and is vulnerable to loss of lock or phase jump. We had a beige-time module, which was intended to be tempered with vcxo, and the result was that the curve was not aligned with the actual drift, but it became increasingly confusing; the tcxo module with the adc and the checklist was then replaced by the tcxo module, which placed the temperature sensors, the compensatory algorithm, the power circuits directly into a 5032-pack, with a small volume, but -30°c to 70°c drifted within ±0. 5 ppm. It's not technical. It's the whole problem with your manual leveling。
It's not enough to just look at the frequency and ppm when you're choosing. One time, i picked a 2016-envelope sting, welded it and found it no longer working. Because the internal load of the mmu is 12 pf, and i've chosen a crystal vibrator that requires 18 pf to be attached, without that 6 pf, the ring is not enough, the amplifier is staring. It was then taken apart and the hand was welded red. Also, esd, the small distance between the tiptips, electrostatic penetration, local penetration of the electrode plating layer, appears to be okay. The measured q value fell from 120,000 to 30,000, the vibrations were slow, the shaking was high, it was not visible with the oscillator, and the spectrometer was used to see the sprawl。
It's a matter of ageing. It's really time to talk. In the same shipment, plant a was aged ± 1 ppm and plant b was rated ± 3 ppm, three years later - two samples from plant a were found to be +0. 8, -0. 9 ppm, and one +2. 6 and the other +4. 1. Not much has expired before life, but slowly it is normal. High-reliability scenarios such as power terminals and high-iron transmitters are now mandatory for ageing test reports, not for what the manufacturer says, but for the raw data you have to get。
Jing was never the most expensive material, but it was the easiest to drag down a whole plate. It doesn't turn on the lights, it doesn't heat, it doesn't report, it's just squeezing at 0. 0001%, and it's not until one day when you find that gps has missed 300 meters, or that 4g modules are not connected to the base station, and you turn back to the logs, change the crystals, recalculate the temperature. And that little silver piece of diamonds, lying still in the corner of the board, even with the welding。
