RR间隔缺少值(BLE / Polar设备)

Question

我有一台Polar H10设备，我对心率和RR-interval很感兴趣，我用安卓的官方蓝牙低能量接口读取了这些数据。Polar设备每秒发送一个带有心率和RR间期的包裹。现在我已经认识到，在每个这样的包中都有一个心率值，但在一些包中没有RR间隔值(RR间隔值是-1)。

这一切为什么要发生？是我的设备坏了，还是我在实现中犯了错误，还是其他人也面临着这个问题？

编辑:这是代码。在public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic)方法中，我从Polar设备接收更改后的值。此方法大约每秒触发一次。然后，我按如下方式解析特征：

    public int[] parse(BluetoothGattCharacteristic characteristic) {

        double heartRate = extractHeartRate(c);
        Integer[] interval = extractBeatToBeatInterval(c);

        int[] result = null;
        if (interval != null) {
            result = new int[interval.length + 1];
        } else {
            result = new int[2];
            result[1] = -1;
        }
        result[0] = (int) heartRate;

        if (interval != null) {
            for (int i = 0; i < interval.length; i++) {
                result[i+1] = interval[i];
            }
        }

        return result;
    }


private static double extractHeartRate(
        BluetoothGattCharacteristic characteristic) {

    int flag = characteristic.getProperties();
    Log.d(TAG, "Heart rate flag: " + flag);
    int format = -1;
    // Heart rate bit number format
    if ((flag & 0x01) != 0) {
        format = BluetoothGattCharacteristic.FORMAT_UINT16;
        Log.d(TAG, "Heart rate format UINT16.");
    } else {
        format = BluetoothGattCharacteristic.FORMAT_UINT8;
        Log.d(TAG, "Heart rate format UINT8.");
    }

    final int heartRate = characteristic.getIntValue(format, 1);
    Log.d(TAG, String.format("Received heart rate: %d", heartRate));
    return heartRate;
}

private static Integer[] extractBeatToBeatInterval(
        BluetoothGattCharacteristic characteristic) {

    int flag = characteristic.getIntValue(BluetoothGattCharacteristic.FORMAT_UINT8, 0);
    int format = -1;
    int energy = -1;
    int offset = 1; // This depends on hear rate value format and if there is energy data
    int rr_count = 0;

    if ((flag & 0x01) != 0) {
        format = BluetoothGattCharacteristic.FORMAT_UINT16;
        Log.d(TAG, "Heart rate format UINT16.");
        offset = 3;
    } else {
        format = BluetoothGattCharacteristic.FORMAT_UINT8;
        Log.d(TAG, "Heart rate format UINT8.");
        offset = 2;
    }
    if ((flag & 0x08) != 0) {
        // calories present
        energy = characteristic.getIntValue(BluetoothGattCharacteristic.FORMAT_UINT16, offset);
        offset += 2;
        Log.d(TAG, "Received energy: {}"+ energy);
    }
    if ((flag & 0x16) != 0){
        // RR stuff.
        Log.d(TAG, "RR stuff found at offset: "+ offset);
        Log.d(TAG, "RR length: "+ (characteristic.getValue()).length);
        rr_count = ((characteristic.getValue()).length - offset) / 2;
        Log.d(TAG, "RR length: "+ (characteristic.getValue()).length);
        Log.d(TAG, "rr_count: "+ rr_count);
        if (rr_count > 0) {
            Integer[] mRr_values = new Integer[rr_count];
            for (int i = 0; i < rr_count; i++) {
                mRr_values[i] = characteristic.getIntValue(
                        BluetoothGattCharacteristic.FORMAT_UINT16, offset);
                offset += 2;
                Log.d(TAG, "Received RR: " + mRr_values[i]);
            }
            return mRr_values;
        }
    }
    Log.d(TAG, "No RR data on this update: ");
    return null;
}

parse方法返回的第一个元素是心率，第二个元素是RR-interval。有时第二个元素是-1 (即没有检测到RR间隔)。