GPS北斗双模技术应用开发研究—数据结构扩展
还是从gps.h头文件入手，首先 GpsSvStatus结构体需要改造，GpsSvStatus当时设计的时候是考虑存储gps卫星信息的，但是我们现在是要存储双模的数据，因此我们需要扩展这个数据结构，那怎么扩展呢？
当然要代价小一点，不能完全推倒重来的，笔者想到的就是增加一个北斗卫星数量的变量，以及北斗的epemeris、almanac、还有一个定位的mask，以前数据结构里面的成员全部用着gps存储，这样就相互独立了，但是sv_list笔者就偷懒共用了，只是把这个数组扩大一倍，后半部分存储北斗卫星信息，这样的话第一步就算完成了。基本如下：
/** Maximum number of SVs for gps_sv_status_callback(). */
-#define GPS_MAX_SVS 32
+#define GPS_MAX_SVS 64
/** Requested operational mode for GPS operation. */
typedef uint32_t GpsPositionMode;
@@ -306,6 +306,25 @@ typedef struct {
* were used for computing the most recent position fix.
*/
uint32_t used_in_fix_mask;
+
+ /** Number of bd SVs currently visible. */
+ int bd_num_svs;
+
+ /** Represents a bit mask indicating which SVs
+ * have ephemeris data.
+ */
+ uint32_t bd_ephemeris_mask;
+
+ /** Represents a bit mask indicating which SVs
+ * have almanac data.
+ */
+ uint32_t bd_almanac_mask;
+
+ /**
+ * Represents a bit mask indicating which SVs
+ * were used for computing the most recent position fix.
+ */
+ uint32_t bd_used_in_fix_mask;
} GpsSvStatus;
解析本身的难度不大，依葫芦画瓢罢了，都是固定的。那就看一下GSV怎么解析的吧!如下：
if ( !memcmp(tok.p, "GSV", 3) ) {
int noSatellites;
Token satellite_to_view;
is_beidou = !memcmp(ptr, "BD", 2);
satellite_to_view = nmea_tokenizer_get(tzer, 3);
noSatellites = str2int(satellite_to_view.p, satellite_to_view.end);
ALOGV(">>>is_beidou (%d) GSV satellite_to_view=%d", is_beidou, noSatellites);
if (noSatellites > 0 ) { //tmp
int sentence, totalSentences, curr, i, bd_cur;
Token num_of_msg;
Token no;
num_of_msg = nmea_tokenizer_get(tzer, 1);
no = nmea_tokenizer_get(tzer, 2);
sentence = str2int(no.p, no.end);
totalSentences = str2int(num_of_msg.p, num_of_msg.end);
D(">>>gsv_index=%d,gsv_total=%d",sentence, totalSentences);
if (sentence == 1 && !is_beidou) {
r->sv_status.num_svs = 0;
r->sv_status.ephemeris_mask = 0ul;
r->sv_status.almanac_mask = 0ul;
r->sv_status.bd_num_svs= 0;
r->sv_status.bd_ephemeris_mask= 0ul;
r->sv_status.bd_almanac_mask= 0ul;
}
curr = r->sv_status.num_svs;
bd_cur = r->sv_status.bd_num_svs + 32;
i = 0;
while (i < 4 && (r->sv_status.num_svs < noSatellites ||
(is_beidou && r->sv_status.bd_num_svs < noSatellites))) {
int prn;
Token tok_prn = nmea_tokenizer_get(tzer, i * 4 + 4);
Token tok_elevation = nmea_tokenizer_get(tzer, i * 4 + 5);
Token tok_azimuth = nmea_tokenizer_get(tzer, i * 4 + 6);
Token tok_snr = nmea_tokenizer_get(tzer, i * 4 + 7);
prn = str2int(tok_prn.p, tok_prn.end);
if (prn <= 0) { i += 1; continue; }
if(is_beidou) {
if(prn > 400)
prn -= 400;//M8 BD base 400
r->sv_status.sv_list[bd_cur].prn = prn;
r->sv_status.sv_list[bd_cur].elevation = str2float(tok_elevation.p, tok_elevation.end);
r->sv_status.sv_list[bd_cur].azimuth = str2float(tok_azimuth.p, tok_azimuth.end);
r->sv_status.sv_list[bd_cur].snr = str2float(tok_snr.p, tok_snr.end);
r->sv_status.bd_ephemeris_mask|= (1ul << (prn-1));
r->sv_status.bd_almanac_mask|= (1ul << (prn-1));
r->sv_status.bd_num_svs+= 1;// bd num
r->sv_status.num_svs += 1;//total num
if(r->sv_status.sv_list[bd_cur].snr > 0)
ALOGV("**bd_cur=%d num_svs:%d prn:%d snr=%f\n", bd_cur, r->sv_status.num_svs,
r->sv_status.sv_list[bd_cur].prn,r->sv_status.sv_list[bd_cur].snr);
bd_cur += 1;
} else {
r->sv_status.sv_list[curr].prn = prn;
r->sv_status.sv_list[curr].elevation = str2float(tok_elevation.p, tok_elevation.end);
r->sv_status.sv_list[curr].azimuth = str2float(tok_azimuth.p, tok_azimuth.end);
r->sv_status.sv_list[curr].snr = str2float(tok_snr.p, tok_snr.end);
r->sv_status.ephemeris_mask |= (1ul << (prn-1));
r->sv_status.almanac_mask |= (1ul << (prn-1));
r->sv_status.num_svs += 1;
if(r->sv_status.sv_list[curr].snr > 0)
ALOGV("##curr=%d num_svs:%d prn:%d snr=%f\n", curr, r->sv_status.num_svs,
r->sv_status.sv_list[curr].prn,r->sv_status.sv_list[curr].snr);
curr += 1;
}
i += 1;
}
其他的GGA这些双模不双模都是一样的。下面我们看看在JNI里面，android_location_GpsLocationProvider_read_sv_status上报的各个卫星的情况的，显示他的接口也是需要改造的，要扩展，如下：
@@ -465,17 +465,34 @@ static jint android_location_GpsLocationProvider_read_sv_status(JNIEnv* env, job
jfloat* elev = env->GetFloatArrayElements(elevArray, 0);
jfloat* azim = env->GetFloatArrayElements(azumArray, 0);
jint* mask = env->GetIntArrayElements(maskArray, 0);
+ int i, j;
int num_svs = sGpsSvStatus.num_svs;
- for (int i = 0; i < num_svs; i++) {
+ int bd_num_svs = sGpsSvStatus.bd_num_svs;
+
+ //gps info
+ for (i = 0; i < (num_svs - bd_num_svs); i++) {
prns[i] = sGpsSvStatus.sv_list[i].prn;
snrs[i] = sGpsSvStatus.sv_list[i].snr;
elev[i] = sGpsSvStatus.sv_list[i].elevation;
azim[i] = sGpsSvStatus.sv_list[i].azimuth;
}
+
+ //bd info
+ for (j = 0; j < bd_num_svs; j++) {
+ prns[i+j] = sGpsSvStatus.sv_list[32+j].prn;
+ snrs[i+j] = sGpsSvStatus.sv_list[32+j].snr;
+ elev[i+j] = sGpsSvStatus.sv_list[32+j].elevation;
+ azim[i+j] = sGpsSvStatus.sv_list[32+j].azimuth;
+ }
+
mask[0] = sGpsSvStatus.ephemeris_mask;
mask[1] = sGpsSvStatus.almanac_mask;
mask[2] = sGpsSvStatus.used_in_fix_mask;
+ mask[3] = bd_num_svs;
+ mask[4] = sGpsSvStatus.bd_ephemeris_mask;
+ mask[5] = sGpsSvStatus.bd_almanac_mask;
+ mask[6] = sGpsSvStatus.bd_used_in_fix_mask; 这个JNI接口直接就得了gps的location provider了，同样要扩展
@@ -1285,7 +1285,9 @@ public class GpsLocationProvider implements LocationProviderInterface {
try {
listener.mListener.onSvStatusChanged(svCount, mSvs, mSnrs,
mSvElevations, mSvAzimuths, mSvMasks[EPHEMERIS_MASK],
- mSvMasks[ALMANAC_MASK], mSvMasks[USED_FOR_FIX_MASK]);
+ mSvMasks[ALMANAC_MASK], mSvMasks[USED_FOR_FIX_MASK],
+ mSvMasks[BD_SVS_NUM], mSvMasks[BD_EPHEMERIS_MASK],
+ mSvMasks[BD_ALMANAC_MASK],mSvMasks[BD_USED_FOR_FIX_MASK]);
} catch (RemoteException e) {
Log.w(TAG, "RemoteException in reportSvInfo");
mListeners.remove(listener);
@@ -1296,22 +1298,33 @@ public class GpsLocationProvider implements LocationProviderInterface {
}
if (VERBOSE) {
- Log.v(TAG, "SV count: " + svCount +
+ Log.d(TAG, "SV count: " + svCount +
" ephemerisMask: " + Integer.toHexString(mSvMasks[EPHEMERIS_MASK]) +
" almanacMask: " + Integer.toHexString(mSvMasks[ALMANAC_MASK]));
for (int i = 0; i < svCount; i++) {
- Log.v(TAG, "sv: " + mSvs[i] +
+ if(i < (svCount - mSvMasks[BD_SVS_NUM])){
+ Log.d(TAG, "sv: " + mSvs[i] +
" snr: " + mSnrs[i]/10 +
" elev: " + mSvElevations[i] +
" azimuth: " + mSvAzimuths[i] +
((mSvMasks[EPHEMERIS_MASK] & (1 << (mSvs[i] - 1))) == 0 ? " " : " E") +
((mSvMasks[ALMANAC_MASK] & (1 << (mSvs[i] - 1))) == 0 ? " " : " A") +
((mSvMasks[USED_FOR_FIX_MASK] & (1 << (mSvs[i] - 1))) == 0 ? "" : "U"));
+ } else {
+
+ Log.d(TAG, "BD sv: " + mSvs[i] +
+ " BD snr: " + mSnrs[i]/10 +
+ " BD elev: " + mSvElevations[i] +
+ " BD azimuth: " + mSvAzimuths[i] +
+ ((mSvMasks[BD_EPHEMERIS_MASK] & (1 << (mSvs[i] - 1))) == 0 ? " " : " E") +
+ ((mSvMasks[BD_ALMANAC_MASK] & (1 << (mSvs[i] - 1))) == 0 ? " " : " A") +
+ ((mSvMasks[BD_USED_FOR_FIX_MASK] & (1 << (mSvs[i] - 1))) == 0 ? "" : "U"));
+ }
}
}
// return number of sets used in fix instead of total
- updateStatus(mStatus, Integer.bitCount(mSvMasks[USED_FOR_FIX_MASK]));
+ updateStatus(mStatus, (Integer.bitCount(mSvMasks[USED_FOR_FIX_MASK] + Integer.bitCount(mSvMasks[BD_USED_FOR_FIX_MASK]))));
if (mNavigating && mStatus == LocationProvider.AVAILABLE && mLastFixTime > 0 &&
System.currentTimeMillis() - mLastFixTime > RECENT_FIX_TIMEOUT) {
@@ -1895,17 +1908,21 @@ public class GpsLocationProvider implements LocationProviderInterface {
}
// for GPS SV statistics
- private static final int MAX_SVS = 32;
+ private static final int MAX_SVS = 64;
private static final int EPHEMERIS_MASK = 0;
private static final int ALMANAC_MASK = 1;
private static final int USED_FOR_FIX_MASK = 2;
+ private static final int BD_SVS_NUM = 3;
+ private static final int BD_EPHEMERIS_MASK = 4;
+ private static final int BD_ALMANAC_MASK = 5;
+ private static final int BD_USED_FOR_FIX_MASK = 6;
// preallocated arrays, to avoid memory allocation in reportStatus()
private int mSvs[] = new int[MAX_SVS];
private float mSnrs[] = new float[MAX_SVS];
private float mSvElevations[] = new float[MAX_SVS];
private float mSvAzimuths[] = new float[MAX_SVS];
- private int mSvMasks[] = new int[3];
+ private int mSvMasks[] = new int[7];
private int mSvCount;
// preallocated to avoid memory allocation in reportNmea()
private byte[] mNmeaBuffer = new byte[120];
这就已经都java部分了，完成了大半了，后面再讲后半段的处理，也还有很多的道道在里面。
