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F9p GNSS

时间:2019-03-20 18:27:39      阅读:679      评论:0      收藏:0      [点我收藏+]

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天线馈电电路,3V供电 有源天线

其它电压有源天线则外接电压

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天线防护

1,ESD

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2,EOS(带无线发射影响)

Electrical Overstress (EOS) usually describes situations when the maximum input power exceeds the maximum specified ratings. EOS failure can happen if RF emitters are close to a GNSS receiver or its antenna. EOS causes damage to the chip structures. If the RF_IN is damaged by EOS, it’s hard to determine whether the chip structures have been damaged by ESD or EOS. EOS protection measures as shown in the figure below are recommended for any designs combining wireless communication transceivers (e.g. GSM, GPRS) and GNSS in the same design or in close proximity.(电过应力(EOS)通常描述为最大输入功率超过规定的最大额定值时的影响。如果RF发射器靠近GNSS接收机或其天线,则会发生EOS干扰故障,这会对芯片结构造成破坏。若芯片RF_IN被EOS破坏,将很难判断芯片结构是否已经被ESD或EOS破坏。建议将无线通讯收发器(例如GSM、GPRS)与GNSS在同一设计或接近设计中组合使用时,采用如下图所示的EOS保护措施)

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3,人身安全

The ZED-F9P must be supplied by an external limited power source in compliance with the clause 2.5 of the standard IEC 60950-1. In addition to external limited power source, only Separated or Safety Extra-Low Voltage (SELV) circuits are to be connected to the module including interfaces and antennas.

4,EMI

4.1 带内干扰

With in-band interference, the signal frequency is very close to the GNSS frequency. Such interference signals are typically caused by harmonics fromdisplays,micro-controller operation, bus systems, etc. Measures against in-band interference include: ? Maintaining a good grounding concept in the design ? Shielding ? Layout optimization ? Low-pass filtering of noise sources, e.g. digital signal lines(

带内干扰下,信号频率与GNSS频率非常接近。该干扰信号通常由显示器、微控制器、总线等系统的谐波引起。

防止带内干扰的措施包括:

?在设计中保持良好的接地观念

?屏蔽

?布局优化

?低通滤波的噪声源,如数字信号线

4.2  带外干扰

Out-of-band interference is caused by signal frequencies that are different from the GNSS carrier frequency. The main sources are wireless communication systems such as LTE, GSM, CDMA, WCDMA, Wi-Fi, BT, etc. Measures against out-of-band interference include maintaining a good grounding concept in the design(设计中良好接地) and adding a GNSS band-pass filter(GNSS带通滤波器)into the antenna input line to the receiver.


PCB布局

1.,天线位置

2,地

3,屏蔽和其他数字设备的干扰位置

4,温度敏感 避免发热器件引起温度漂移和空气对流

天线阻抗

For FR-4 PCB material with a dielectric permittivity of for example 4.7 we can calculate the trace width at 1575 MHz for 50 Ω impedance.

(传输线阻抗50Ω)

1,PCB特征阻抗计算神器Polar SI9000 计算

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线宽 要50mil coated coplanar waveguide with ground 1B 模型

2,公式计算


设计注意:

Do not load Pin 4 (ANT_DETECT) with a capacitance more than 1 nF. Check power supply requirements and schematic: ? Is the power supply voltage within the specified range? ? If USB is not used, connect the V_USB pin to ground. ? If USB is used, is there a 1 uF and a 100 nF capacitor right near the V_USB pin? This is just for the V_USB pin. ? Is there a 1 uF cap right next to the module VCC pin? ? Compare the peak current consumption of the ZED-F9P GNSS module with the specification of your power supply. ? GNSS receivers require a stable power supply. Avoid series resistance (less than 0.2 Ω) in your power supply line (the line to VCC) to minimize the voltage ripple on VCC. ? Allow all I/O to Float/High impedance when VCC is not applied. See "Interfaces" section

不要加载电容大于1nf的引脚4 (ant_detection)。检查电源要求及原理图:
?电源电压是否在规定范围内?
?如果不使用USB,将V_USB引脚连接到地面。
?如果使用USB, V_USB引脚附近是否有一个1uf和一个100nf电容?这只是为V_USB pin。
?模块VCC引脚旁边是否有一个1uf覆盖?
?将ZED-F9P GNSS模块的峰值电流消耗与您的电源规格进行比较。
?GNSS接收机需要稳定的电源。避免串联电阻(小于0.2Ω)在你的供电线(线VCC)最小化VCC电压纹波。
?当不使用VCC时,允许所有I/O浮动/高阻抗。

F9p GNSS

原文:https://www.cnblogs.com/xiumusheng/p/10566588.html

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